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Lonergan PE, Vertosick EA, Assel M, Sjoberg DD, Haese A, Graefen M, Boorjian SA, Klee GG, Cooperberg MR, Pettersson K, Routila E, Vickers AJ, Lilja H. Prospective validation of microseminoprotein-β added to the 4Kscore in predicting high-grade prostate cancer in an international multicentre cohort. BJU Int 2021; 128:218-224. [PMID: 33306251 PMCID: PMC8279428 DOI: 10.1111/bju.15320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To prospectively evaluate the performance of a pre-specified statistical model based on four kallikrein markers in blood (total prostate-specific antigen [PSA], free PSA, intact PSA, and human kallikrein-related peptidase 2), commercially available as the 4Kscore, in predicting Gleason Grade Group (GG) ≥2 prostate cancer at biopsy in an international multicentre study at three academic medical centres, and whether microseminoprotein-β (MSP) adds predictive value. PATIENTS AND METHODS A total of 984 men were prospectively enrolled at three academic centres. The primary outcome was GG ≥2 on prostate biopsy. Three pre-specified statistical models were used: a base model including PSA, age, digital rectal examination and prior negative biopsy; a model that added free PSA to the base model; and the 4Kscore. RESULTS A total of 947 men were included in the final analysis and 273 (29%) had GG ≥2 on prostate biopsy. The base model area under the receiver operating characteristic curve of 0.775 increased to 0.802 with the addition of free PSA, and to 0.824 for the 4Kscore. Adding MSP to the 4Kscore model yielded an increase (0.014-0.019) in discrimination. In decision-curve analysis of clinical utility, the 4Kscore showed a benefit starting at a 7.5% threshold. CONCLUSION A prospective multicentre evaluation of a pre-specified model based on four kallikrein markers (4Kscore) with the addition of MSP improves the predictive discrimination for GG ≥2 prostate cancer on biopsy and could be used to inform biopsy decision-making.
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Affiliation(s)
- Peter E Lonergan
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Emily A Vertosick
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Melissa Assel
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel D Sjoberg
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexander Haese
- Martini-Klinik Prostate Cancer Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Markus Graefen
- Martini-Klinik Prostate Cancer Center, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | | | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Matthew R Cooperberg
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - Kim Pettersson
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Erica Routila
- Departments of Biochemistry/Biotechnology, University of Turku, Turku, Finland
| | - Andrew J Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hans Lilja
- Departments of Laboratory Medicine, Surgery, and Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Translational Medicine, Lund University, Malmö, Sweden
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Assel MJ, Ulmert HD, Karnes RJ, Boorjian SA, Hillman DW, Vickers AJ, Klee GG, Lilja H. Kallikrein markers performance in pretreatment blood to predict early prostate cancer recurrence and metastasis after radical prostatectomy among very high-risk men. Prostate 2020; 80:51-56. [PMID: 31603253 PMCID: PMC6944058 DOI: 10.1002/pros.23916] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 09/26/2019] [Indexed: 12/30/2022]
Abstract
BACKGROUND To assess whether a prespecified statistical model based on the four kallikrein markers measured in blood-total, free, and intact prostate-specific antigen (PSA), together with human kallikrein-related peptidase 2 (hK2)-or any individual marker measured in pretreatment serum were associated with biochemical recurrence-free (BCR) or metastasis-free survival after radical prostatectomy (RP) in a subgroup of men with very high-risk disease. METHODS We identified 106 men treated at Mayo Clinic from 2004 to 2008 with pathological Gleason grade group 4 to 5 or seminal vesicle invasion at RP. Univariable and multivariable Cox models were used to test the association between standard predictors (Kattan nomogram and GPSM [Gleason, PSA, seminal vesicle and margin status] score), kallikrein panel, and individual kallikrein markers with the outcomes. RESULTS BCR and metastasis occurred in 67 and 30 patients, respectively. The median follow-up for patients who did not develop a BCR was 10.3 years (interquartile range = 8.2-11.8). In this high-risk group, neither Kattan risk, GPSM score, or the kallikrein panel model was associated with either outcome. However, after adjusting for Kattan risk and GPSM score, separately, preoperative intact PSA was associated with both outcomes while hK2 was associated with metastasis-free survival. CONCLUSIONS Conventional risk prediction tools were poor discriminators for risk of adverse outcomes after RP (Kattan risk and GPSM risk) in patients with very high-risk disease. Further studies are needed to define the role of individual kallikrein marker forms in the blood to predict adverse prostate cancer outcomes after RP in this high-risk setting.
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Affiliation(s)
- Melissa J. Assel
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hans David Ulmert
- Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
- Department of Translational Medicine, Lund University, Malmö, Sweden
| | | | | | - David W. Hillman
- Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA
| | - Andrew J. Vickers
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - George G. Klee
- Mayo Clinic College of Medicine & Science, Mayo Clinic, Rochester, MN, USA
| | - Hans Lilja
- Departments of Laboratory Medicine, Surgery, and Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
- Department of Translational Medicine, Lund University, Malmö, Sweden
- Corresponding author: Hans Lilja, MD, PhD, 1275 York Ave, BOX 213, New York, NY 10065, (P) 212-639-6982, (F) 646-422-2379,
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Klee GG, Ichihara K, Ozarda Y, Baumann NA, Straseski J, Bryant SC, Wood-Wentz CM. Reference Intervals: Comparison of Calculation Methods and Evaluation of Procedures for Merging Reference Measurements From Two US Medical Centers. Am J Clin Pathol 2018; 150:545-554. [PMID: 30169553 DOI: 10.1093/ajcp/aqy082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To analyze consistency of reference limits and widths of reference intervals (RIs) calculated by six procedures and evaluate a protocol for merging intrainstitutional reference data. METHODS The differences between reference limits were compared with "optimal" bias goals. Also, widths of the RIs were compared. RIs were calculated using Mayo-SAS quantile, EP Evaluator, and four International Federation of Clinical Chemistry and Laboratory Medicine methods: parametric and nonparametric (NP) with and without latent abnormal values exclusion (LAVE). Regression parameters from cotested samples were evaluated for harmonizing intrainstitutional reference data. RESULTS Mayo-SAS quintile, LAVE(-)NP, and EP Evaluator generated similar RIs, but these RIs often were wider than RIs from parametric procedures. LAVE procedures generated narrower RIs for nutritional and inflammatory markers. Transformation with regression parameters did not ensure homogeneity of merged data. CONCLUSIONS Parametric methods are recommended when inappropriate values cannot be excluded. The nonparametric procedures may generate wider RIs. Data sets larger than 200 are recommended for robust estimates. Caution should be exercised when merging intrainstitutional data.
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Affiliation(s)
- George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | | | - Nikola A Baumann
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | - Sandra C Bryant
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN
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Veldhuis JD, Dyer RB, Trushin SA, Bondar OP, Singh RJ, Klee GG. Interleukins 6 and 8 and abdominal fat depots are distinct correlates of lipid moieties in healthy pre- and postmenopausal women. Endocrine 2016; 54:671-680. [PMID: 27444747 PMCID: PMC5107333 DOI: 10.1007/s12020-016-1041-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 06/27/2016] [Indexed: 01/24/2023]
Abstract
UNLABELLED Available data associate lipids concentrations in men with body mass index, anabolic steroids, age, and certain cytokines. Data were less clear in women, especially across the full adult lifespan, and when segmented by premenopausal and postmenopausal status. SUBJECTS 120 healthy women (60 premenopausal and 60 postmenopausal) in Olmsted County, MN, USA, a stable well studied clinical population. Dependent variables: measurements of 10 h fasting high-density lipoprotein cholesterol, total cholesterol, low-density lipoprotein cholesterol, and triglycerides. INDEPENDENT VARIABLES testosterone, estrone, estradiol, 5-alpha-dihydrotestosterone, and sex-hormone binding globulin (by mass spectrometry); insulin, glucose, and albumin; abdominal visceral, subcutaneous, and total abdominal fat [abdominal visceral fat, subcutaneous fat, total abdominal fat by computerized tomography scan]; and a panel of cytokines (by enzyme-linked immunosorbent assay). Multivariate forward-selection linear-regression analysis was applied constrained to P < 0.01. Lifetime data: High-density lipoprotein cholesterol was correlated jointly with age (P < 0.0001, positively), abdominal visceral fat (P < 0.0001, negatively), and interleukin-6 (0.0063, negatively), together explaining 28.1 % of its variance (P = 2.3 × 10-8). Total cholesterol was associated positively with multivariate age only (P = 6.9 × 10-4, 9.3 % of variance). Triglycerides correlated weakly with sex-hormone binding globulin (P = 0.0115), and strongly with abdominal visceral fat (P < 0.0001), and interleukin-6 (P = 0.0016) all positively (P = 1.6 × 10-12, 38.9 % of variance). Non high-density lipoprotein cholesterol and low-density lipoprotein cholesterol correlated positively with both total abdominal fat and interleukin-8 (P = 2.0 × 10-5, 16.9 % of variance; and P = 0.0031, 9.4 % of variance, respectively). Premenopausal vs. postmenopausal comparisons identified specific relationships that were stronger in premenopausal than postmenopausal individuals, and vice versa. Age was a stronger correlate of low-density lipoprotein cholesterol; interleukin-6 of triglycerides and high-density lipoprotein; and both sex-hormone binding globulin and total abdominal fat of non high-density lipoprotein cholesterol in premenopausal than postmenopausal women. Conversely, sex-hormone binding globulin, abdominal visceral fat, interleukin-8, adiponectin were stronger correlates of triglycerides; abdominal visceral fat, and testosterone of high-density lipoprotein cholesterol; and age of both non high-density lipoprotein and low-density lipoprotein in postmenopausal than premenopausal women. Our data delineate correlations of total abdominal fat and interleukin-8 (both positively) with non high-density lipoprotein cholesterol and low-density lipoprotein cholesterol in healthy women across the full age range of 21-79 years along with even more specific associations in premenopausal and postmenopausal individuals. Whether some of these outcomes reflect causal relationships would require longitudinal and interventional or genetic studies.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Roy B Dyer
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
| | - Sergey A Trushin
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
- Department of Neurology, 200 First Street SW, Rochester, MN, 55905, USA
| | - Olga P Bondar
- Immunochemical Laboratory, 200 First Street SW, Rochester, MN, 55905, USA
| | - Ravinder J Singh
- Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - George G Klee
- Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
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Akbas N, Budd JR, Klee GG. Multiple calibrator measurements improve accuracy and stability estimates of automated assays. Scandinavian Journal of Clinical and Laboratory Investigation 2016; 76:177-80. [DOI: 10.3109/00365513.2015.1126760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Spratt DE, Evans MJ, Davis BJ, Doran MG, Lee MX, Shah N, Wongvipat J, Carnazza KE, Klee GG, Polkinghorn W, Tindall DJ, Lewis JS, Sawyers CL. Androgen Receptor Upregulation Mediates Radioresistance after Ionizing Radiation. Cancer Res 2015; 75:4688-96. [PMID: 26432404 DOI: 10.1158/0008-5472.can-15-0892] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 08/11/2015] [Indexed: 12/19/2022]
Abstract
Clinical trials have established the benefit of androgen deprivation therapy (ADT) combined with radiotherapy in prostate cancer. ADT sensitizes prostate cancer to radiotherapy-induced death at least in part through inhibition of DNA repair machinery, but for unknown reasons, adjuvant ADT provides further survival benefits. Here, we show that androgen receptor (AR) expression and activity are durably upregulated following radiotherapy in multiple human prostate cancer models in vitro and in vivo. Moreover, the degree of AR upregulation correlates with survival in vitro and time to tumor progression in animal models. We also provide evidence of AR pathway upregulation, measured by a rise in serum levels of AR-regulated hK2 protein, in nearly 20% of patients after radiotherapy. Furthermore, these men were three-fold more likely to experience subsequent biochemical failure. Collectively, these data demonstrate that radiotherapy can upregulate AR signaling after therapy to an extent that negatively affects disease progression and/or survival.
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Affiliation(s)
- Daniel E Spratt
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York. Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York. Department of Radiology and Molecular the Molecular Pharmacology & Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Michael J Evans
- Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Brian J Davis
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Michael G Doran
- Department of Radiology and Molecular the Molecular Pharmacology & Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Man Xia Lee
- Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Neel Shah
- Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - John Wongvipat
- Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Kathryn E Carnazza
- Department of Radiology and Molecular the Molecular Pharmacology & Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - George G Klee
- Departments of Urology and Biochemistry/Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - William Polkinghorn
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York. Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Donald J Tindall
- Departments of Urology and Biochemistry/Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Jason S Lewis
- Department of Radiology and Molecular the Molecular Pharmacology & Chemistry Program, Memorial Sloan Kettering Cancer Center, New York, New York.
| | - Charles L Sawyers
- Human Oncology Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York.
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7
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Klee EW, Bondar OP, Goodmanson MK, Trushin SA, Bergstralh EJ, Singh RJ, Anderson NL, Klee GG. Serum concentrations of prostate-specific antigen measured using immune extraction, trypsin digestion, and tandem mass spectrometry quantification of LSEPAELTDAVK peptide. Arch Pathol Lab Med 2014; 138:1381-6. [PMID: 25268201 DOI: 10.5858/arpa.2013-0462-oa] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Prostate-specific antigen (PSA) is a 34-kDa glycoprotein with chymotrypsin-like enzyme activity that circulates both in free forms and complexed to various enzyme inhibitors including antichymotrypsin and α2-macroglobulin. Prostate-specific antigen bound to α2-macroglobulin is not detected by commercial PSA immunoassays. OBJECTIVE To develop a mass spectrometry assay that detects the same forms of PSA as the immunoassays, which could serve as a reference for harmonizing PSA immunoassays. DESIGN Prostate-specific antigen was immune extracted from serum, trypsin was digested, and the LSEPAELTDAVK peptide was quantitated on an API 5000 spectrometer. Calibrators were made by adding 10% free and 90% antichymotrypsin-bound PSA to female sera. The assay was standardized to the World Health Organization 96/670 reference standard. Validation of clinical utility and comparisons with 2 immunoassays (Roche cobas and Beckman Access) were performed using frozen sera aliquots from 100 men undergoing prostate biopsy (50 negative, 50 with cancer) and 5 serial samples collected over time from 5 men with advanced prostate cancer. RESULTS The antibody extraction efficiency was greater than 99%. The assay has an analytic range from 1.2 to 76 ng/mL, with precision ranging from 8.6% at 1.5 ng/mL to 5.4% at 27 ng/mL. The mass spectrometry assay correlated well with 2 immunoassays. All 3 assays showed statistically equivalent separation of prostate cancer from benign disease using receiver operating characteristic curve analysis. CONCLUSIONS This mass spectrometry assay can reliably measure PSA concentrations in human serum and could serve as a reference standard for harmonizing PSA immunoassays.
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Affiliation(s)
- Eric W Klee
- From the Departments of Health Sciences Research (Dr E. Klee and Mr Bergstralh) and Laboratory Medicine and Pathology (Drs Bondar, Trushin, Singh, and G. Klee and Ms. Goodmanson), Mayo Clinic College of Medicine, Rochester, Minnesota; and the Plasma Proteome Institute, Washington, DC (Dr Anderson)
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Killeen AA, Long T, Souers R, Styer P, Ventura CB, Klee GG. Verifying performance characteristics of quantitative analytical systems: calibration verification, linearity, and analytical measurement range. Arch Pathol Lab Med 2014; 138:1173-81. [PMID: 25171699 DOI: 10.5858/arpa.2013-0051-cp] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT Both the regulations in the Clinical Laboratory Improvement Amendments of 1988 (CLIA) and the checklists of the College of American Pathologists (CAP) Laboratory Accreditation Program require clinical laboratories to verify performance characteristics of quantitative test systems. Laboratories must verify performance claims when introducing an unmodified, US Food and Drug Administration-cleared or approved test system, and they must comply with requirements for periodic calibration and calibration verification for existing test systems. They must also periodically verify the analytical measurement range of many quantitative test systems. OBJECTIVE To provide definitions for many of the terms used in these regulations, to describe a set of basic analyses that laboratories may adapt to demonstrate compliance with both CLIA and the CAP Laboratory Accreditation Program checklists for performing calibration verification and for verifying the analytical measurement range of test systems, to review some of the recommended procedures for establishing performance goals, and to provide data illustrating the performance goals used in some of the CAP's calibration verification and linearity surveys. DATA SOURCES The CAP's calibration verification and linearity survey programs, the CLIA regulations, the Laboratory Accreditation Program requirements, and published literature were used to meet these objectives. CONCLUSIONS Calibration verification and linearity and analytical measurement range verification should be performed using suitable materials with assessment of results using well-defined evaluation protocols. We describe the CAP's calibration verification and linearity programs that may be used for these purposes.
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Affiliation(s)
- Anthony A Killeen
- From the Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis (Dr Killeen); the Department of Biostatistics (Mr Long, Ms Souers, and Dr Styer) and the Instrumentation Resource Committee (Ms Ventura), College of American Pathologists, Northfield, Illinois; and the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota (Dr Klee)
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9
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Akbas N, Schryver PG, Algeciras-Schimnich A, Baumann NA, Block DR, Budd JR, Gaston SJS, Klee GG. Evaluation of Beckman Coulter DxI 800 immunoassay system using clinically oriented performance goals. Clin Biochem 2014; 47:158-63. [PMID: 25130957 DOI: 10.1016/j.clinbiochem.2014.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/01/2014] [Accepted: 08/04/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVES We evaluated the analytical performance of 24 immunoassays using the Beckman Coulter DxI 800 immunoassay systems at Mayo Clinic, Rochester, MN for trueness, precision, detection limits, linearity, and consistency (across instruments and reagent lots). METHODS Clinically oriented performance goals were defined using the following methods: trueness-published desirable accuracy limits, precision-published desirable biologic variation; detection limits - 0.1 percentile of patient test values, linearity - 50% of total error, and consistency-percentage test values crossing key decision points. Local data were collected for precision, linearity, and consistency. Data were provided by Beckman Coulter, Inc. for trueness and detection limits. RESULTS All evaluated assays except total thyroxine were within the proposed goals for trueness. Most of the assays met the proposed goals for precision (86% of intra-assay results and 75% of inter-assay results). Five assays had more than 15% of the test results below the minimum detection limits. Carcinoembryonic antigen, total thyroxine and free triiodothyronine exceeded the proposed goals of ±6.3%, ±5% and ±5.7% for dilution linearity. All evaluated assays were within the proposed goals for instrument consistency. Lot-to-lot consistency results for cortisol, ferritin and total thyroxine exceeded the proposed goals of 3.3%, 11.4% and 7% at one medical decision level, while vitamin B12 exceeded the proposed goals of 5.2% and 3.8% at two decision levels. CONCLUSIONS The Beckman Coulter DxI 800 immunoassay system meets most of these proposed goals, even though these clinically focused performance goals represent relatively stringent limits.
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Affiliation(s)
- Neval Akbas
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | | | | | - Nikola A Baumann
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Darci R Block
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | | | | | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
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Lu J, Lonergan PE, Nacusi LP, Wang L, Schmidt LJ, Sun Z, Van der Steen T, Boorjian SA, Kosari F, Vasmatzis G, Klee GG, Balk SP, Huang H, Wang C, Tindall DJ. The cistrome and gene signature of androgen receptor splice variants in castration resistant prostate cancer cells. J Urol 2014; 193:690-8. [PMID: 25132238 DOI: 10.1016/j.juro.2014.08.043] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2014] [Indexed: 01/23/2023]
Abstract
PURPOSE Spliced variant forms of androgen receptor were recently identified in castration resistant prostate cancer cell lines and clinical samples. We identified the cistrome and gene signature of androgen receptor splice variants in castration resistant prostate cancer cell lines and determined the clinical significance of androgen receptor splice variant regulated genes. MATERIALS AND METHODS The castration resistant prostate cancer cell line 22Rv1, which expresses full-length androgen receptor and androgen receptor splice variants endogenously, was used as the research model. We established 22Rv1-ARFL(-)/ARV(+) and 22Rv1-ARFL(-)/ARV(-) through RNA interference. Chromatin immunoprecipitation coupled with next generation sequencing and microarray techniques were used to identify the cistrome and gene expression profiles of androgen receptor splice variants in the absence of androgen. RESULTS Androgen receptor splice variant binding sites were identified in 22Rv1-ARFL(-)/ARV(+). A gene set was regulated uniquely by androgen receptor splice variants but not by full-length androgen receptor in the absence of androgen. Integrated analysis revealed that some genes were directly modulated by androgen receptor splice variants. Unsupervised clustering analysis showed that the androgen receptor splice variant gene signature differentiated benign from malignant prostate tissue as well as localized prostate cancer from metastatic castration resistant prostate cancer specimens. Some genes that were modulated uniquely by androgen receptor splice variants also correlated with histological grade and biochemical failure. CONCLUSIONS Androgen receptor splice variants can bind to DNA independent of full-length androgen receptor in the absence of androgen and modulate a unique set of genes that is not regulated by full-length androgen receptor. The androgen receptor splice variant gene signature correlates with disease progression. It distinguishes primary cancer from castration resistant prostate cancer specimens and benign from malignant prostate specimens.
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Affiliation(s)
- Ji Lu
- Department of Urology, First Hospital of Jilin University, Changchun, People's Republic of China; Department of Urology, Mayo Clinic, Rochester, Minnesota
| | | | - Lucas P Nacusi
- Department of Urology, Mayo Clinic, Rochester, Minnesota
| | - Liguo Wang
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota
| | - Lucy J Schmidt
- Department of Urology, Mayo Clinic, Rochester, Minnesota
| | - Zhifu Sun
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota
| | | | | | - Farhad Kosari
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - George Vasmatzis
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Steven P Balk
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Haojie Huang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Chunxi Wang
- Department of Urology, First Hospital of Jilin University, Changchun, People's Republic of China.
| | - Donald J Tindall
- Department of Urology, Mayo Clinic, Rochester, Minnesota; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota.
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11
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Veldhuis JD, Dyer RB, Trushin SA, Bondar OP, Singh RJ, Klee GG. Immunologic and mass-spectrometric estimates of SHBG concentrations in healthy women. Metabolism 2014; 63:783-92. [PMID: 24746136 PMCID: PMC4066221 DOI: 10.1016/j.metabol.2014.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 03/07/2014] [Accepted: 03/17/2014] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Sex-hormone binding globulin (SHBG) concentrations across the adult female lifespan are not well defined. To address this knowledge gap, SHBG was quantified by both immunological and criterion methods, viz, mass spectrometry (MS). SETTING Center for Translational Science Activities (CTSA). PARTICIPANTS Healthy nonpregnant women (N=120) ages 21 to 79 years. OUTCOMES SHBG, testosterone (T), estradiol (E2) and estrone (E1) each determined by MS. Uni- and multivariate regression of SHBG concentrations on age, body mass index (BMI), total and visceral abdominal fat (TAF, AVF), albumin, glucose, insulin, sex steroids, selected cytokines, blood pressure, and lipids. RESULTS By univariate regression, MS-estimated SHBG correlated negatively with BMI, TAF, AVF, insulin, free T and bioavailable T (bio T) (each P≤10(-4)), but not with blood pressure or lipids. By stepwise multivariate regression analysis, free and total T (both positive) and bio T (negative) were correlated with SHBG in all 4 assays (each P<10(-15), R(2)≥0.481). In addition, TAF and BMI were negatively associated with SHBG (P≤0.0066) in 2 SHBG assays, and estrone and IL-8 with SHBG weakly (P≤0.035) in one SHBG assay each. When nonsignificant cytokines were excluded, SHBG was jointly associated with AVF, total T and HDL (P<10(-9), R(2)=0.358). CONCLUSION According to MS, three metabolic factors, T, AVF and HDL, together explain more than one-third of the interindividual variation in SHBG levels. We speculate that these measures reflect insulin action.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit, Mayo School of Graduate Medical Education, Mayo Clinic, Rochester, MN 55905.
| | - Roy B Dyer
- Immunochemical Laboratory, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Sergey A Trushin
- Immunochemical Laboratory, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905; Department of Neurology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Olga P Bondar
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - Ravinder J Singh
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
| | - George G Klee
- Laboratory Medicine and Pathology, Center for Translational Science Activities, Mayo Clinic, Rochester, MN 55905
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Hyltoft Petersen P, Klee GG. Reprint of "Influence of analytical bias and imprecision on the number of false positive results using Guideline-Driven Medical Decision Limits". Clin Chim Acta 2014; 432:127-34. [PMID: 24747109 DOI: 10.1016/j.cca.2014.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/23/2013] [Accepted: 12/11/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Diagnostic decisions based on decision limits according to medical guidelines are different from the majority of clinical decisions due to the strict dichotomization of patients into diseased and non-diseased. Consequently, the influence of analytical performance is more critical than for other diagnostic decisions where much other information is included. The aim of this opinion paper is to investigate consequences of analytical quality and other circumstances for the outcome of "Guideline-Driven Medical Decision Limits". TERMS Effects of analytical bias and imprecision should be investigated separately and analytical quality specifications should be estimated accordingly. BIOLOGICAL VARIATION AND ANALYTICAL PERFORMANCE Use of sharp decision limits doesn't consider biological variation and effects of this variation are closely connected with the effects of analytical performance. Such relationships are investigated for the guidelines for HbA1c in diagnosis of diabetes and in risk of coronary heart disease based on serum cholesterol. The effects of a second sampling in diagnosis give dramatic reduction in the effects of analytical quality showing minimal influence of imprecision up to 3 to 5% for two independent samplings, whereas the reduction in bias is more moderate and a 2% increase in concentration doubles the percentage of false positive diagnoses, both for HbA1c and cholesterol. FREQUENCY OF FOLLOW-UP LABORATORY TESTS An alternative approach comes from the current application of guidelines for follow-up laboratory tests according to clinical procedure orders, e.g. frequency of parathyroid hormone requests as a function of serum calcium concentrations. Here, the specifications for bias can be evaluated from the functional increase in requests for increasing serum calcium concentrations. PROBABILITY FUNCTION FOR DIAGNOSES In consequence of the difficulties with biological variation and the practical utilization of concentration dependence of frequency of follow-up laboratory tests already in use, a kind of probability function for diagnosis as function of the key-analyte is proposed.
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Affiliation(s)
- Per Hyltoft Petersen
- The Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Section for General Practice, Department of Public Health and Primary Health Care, Faculty of Medicine and Dentistry, University of Bergen, Norway.
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
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13
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Klee EW, Bondar OP, Goodmanson MK, Trushin SA, Singh RJ, Anderson NL, Klee GG. Mass spectrometry measurements of prostate-specific antigen (PSA) peptides derived from immune-extracted PSA provide a potential strategy for harmonizing immunoassay differences. Am J Clin Pathol 2014; 141:527-33. [PMID: 24619754 DOI: 10.1309/ajcp8pel0yxahdvk] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES Harmonization of prostate-specific antigen (PSA) immunoassays is important for good patient care. The specificity of the antibodies used to detect circulating PSA could cause differences in the PSA measurements. METHODS We used mass spectrometry (MS) to quantitate the concentration of five peptides cleaved from trypsin digestion of PSA and compared these measurements with six automated immunoassays. Linear regression and a mixed-effects model were used to analyze the results. RESULTS PSA measurements from the immunoassays and the five MS peptide assays were highly correlated (R(2) > 0.99), but the recovery of the World Health Organization standard and the regression slopes differed across assays. The same relative patterns of immunoassay differences were seen in comparing their results with each of the five MS peptide measurements from different parts of the circulating PSA molecules. CONCLUSIONS Mass spectrometry quantitation of peptides derived from trypsin digestion of immune-extracted PSA could be used to harmonize PSA immunoassays.
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14
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Veldhuis JD, Bondar OP, Dyer RB, Trushin SA, Klee EW, Singh RJ, Klee GG. Immunological and mass spectrometric assays of SHBG: consistent and inconsistent metabolic associations in healthy men. J Clin Endocrinol Metab 2014; 99:184-93. [PMID: 24203061 PMCID: PMC3879680 DOI: 10.1210/jc.2013-2642] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT SHBG concentrations correlate inconsistently with metabolic parameters. HYPOTHESIS SHBG assay platforms contribute to nonuniformities according to the literature. DESIGN The design of the study was a noninterventional quantification of SHBG by two immuno- and two mass spectrometric assays and abdominal visceral fat by computed tomography scan. SETTING The study was conducted at the Center for Translational Science Activities. PARTICIPANTS Healthy men (n=120) aged 18-80 years with a body mass index of 20-43 kg/m2 participated I the study. OUTCOMES Outcomes of the study included a correlation of log SHBG with age, metabolic surrogates [body mass index, albumin, glucose, insulin, abdominal (total and visceral) fat, homeostasis model assessment insulin resistance index], sex steroids (estrone, 17β-estradiol, T, and dihydrotestosterone by mass spectrometry), and adipocytokines (IL-1β, IL-6, IL-8, IL-10 and IL-12, TNF-α, and adiponectin). RESULTS By univariate regression, age (P<10(-4)), dihydrotestosterone (P<10(-4)), T (P≤.00022), and adiponectin (P≤.0084) were positive correlates, and insulin and homeostasis model assessment insulin resistance index were negative correlates (P≤.0060) of SHBG in all four assays. Stepwise multivariate analysis unveiled that age and T together could explain 38.1%-52.5% of the statistical variance in SHBG in all assays (P<10(-11)). Multivariate regression without sex steroids unveiled that age (P<10(-5)) and insulin (P<10(-3)) are jointly associated with SHBG levels in the four assays with overall R2=0.215-0.293 and P<10(-6). In one immunological SHBG assay each, abdominal visceral fat and adiponectin were weak multivariates also. CONCLUSION Immunological and mass spectrometric SHBG assays yield both consistent and inconsistent correlations with key metabolic variables in healthy men, thereby potentially explaining earlier inconsistencies in the literature.
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Affiliation(s)
- Johannes D Veldhuis
- Endocrine Research Unit (J.D.V.), Mayo School of Graduate Medical Education Center for Translational Science Activities, Immunochemical Laboratory (R.B.D.), and Departments of Neurology (S.A.T.) and Laboratory Medicine and Pathology (J.D.V., O.P.B., E.W.K., R.J.S., G.G.K.), Mayo Clinic, Rochester, Minnesota 55905
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15
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Hyltoft Petersen P, Klee GG. Influence of analytical bias and imprecision on the number of false positive results using Guideline-Driven Medical Decision Limits. Clin Chim Acta 2013; 430:1-8. [PMID: 24362233 DOI: 10.1016/j.cca.2013.12.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/23/2013] [Accepted: 12/11/2013] [Indexed: 01/14/2023]
Abstract
BACKGROUND Diagnostic decisions based on decision limits according to medical guidelines are different from the majority of clinical decisions due to the strict dichotomization of patients into diseased and non-diseased. Consequently, the influence of analytical performance is more critical than for other diagnostic decisions where much other information is included. The aim of this opinion paper is to investigate consequences of analytical quality and other circumstances for the outcome of "Guideline-Driven Medical Decision Limits". TERMS Effects of analytical bias and imprecision should be investigated separately and analytical quality specifications should be estimated accordingly. BIOLOGICAL VARIATION AND ANALYTICAL PERFORMANCE Use of sharp decision limits doesn't consider biological variation and effects of this variation are closely connected with the effects of analytical performance. Such relationships are investigated for the guidelines for HbA1c in diagnosis of diabetes and in risk of coronary heart disease based on serum cholesterol. The effects of a second sampling in diagnosis give dramatic reduction in the effects of analytical quality showing minimal influence of imprecision up to 3 to 5% for two independent samplings, whereas the reduction in bias is more moderate and a 2% increase in concentration doubles the percentage of false positive diagnoses, both for HbA1c and cholesterol. FREQUENCY OF FOLLOW-UP LABORATORY TESTS An alternative approach comes from the current application of guidelines for follow-up laboratory tests according to clinical procedure orders, e.g. frequency of parathyroid hormone requests as a function of serum calcium concentrations. Here, the specifications for bias can be evaluated from the functional increase in requests for increasing serum calcium concentrations. PROBABILITY FUNCTION FOR DIAGNOSES In consequence of the difficulties with biological variation and the practical utilization of concentration dependence of frequency of follow-up laboratory tests already in use, a kind of probability function for diagnosis as function of the key-analyte is proposed.
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Affiliation(s)
- Per Hyltoft Petersen
- The Norwegian Quality Improvement of Primary Care Laboratories (NOKLUS), Section for General Practice, Department of Public Health and Primary Health Care, Faculty of Medicine and Dentistry, University of Bergen, Norway.
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
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16
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Karnes RJ, Bergstralh EJ, Davicioni E, Ghadessi M, Buerki C, Mitra AP, Crisan A, Erho N, Vergara IA, Lam LL, Carlson R, Thompson DJS, Haddad Z, Zimmermann B, Sierocinski T, Triche TJ, Kollmeyer T, Ballman KV, Black PC, Klee GG, Jenkins RB. Validation of a genomic classifier that predicts metastasis following radical prostatectomy in an at risk patient population. J Urol 2013; 190:2047-53. [PMID: 23770138 PMCID: PMC4097302 DOI: 10.1016/j.juro.2013.06.017] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2013] [Indexed: 01/17/2023]
Abstract
PURPOSE Patients with locally advanced prostate cancer after radical prostatectomy are candidates for secondary therapy. However, this higher risk population is heterogeneous. Many cases do not metastasize even when conservatively managed. Given the limited specificity of pathological features to predict metastasis, newer risk prediction models are needed. We report a validation study of a genomic classifier that predicts metastasis after radical prostatectomy in a high risk population. MATERIALS AND METHODS A case-cohort design was used to sample 1,010 patients after radical prostatectomy at high risk for recurrence who were treated from 2000 to 2006. Patients had preoperative prostate specific antigen greater than 20 ng/ml, Gleason 8 or greater, pT3b or a Mayo Clinic nomogram score of 10 or greater. Patients with metastasis at diagnosis or any prior treatment for prostate cancer were excluded from analysis. A 20% random sampling created a subcohort that included all patients with metastasis. We generated 22-marker genomic classifier scores for 219 patients with available genomic data. ROC and decision curves, competing risk and weighted regression models were used to assess genomic classifier performance. RESULTS The genomic classifier AUC was 0.79 for predicting 5-year metastasis after radical prostatectomy. Decision curves showed that the genomic classifier net benefit exceeded that of clinical only models. The genomic classifier was the predominant predictor of metastasis on multivariable analysis. The cumulative incidence of metastasis 5 years after radical prostatectomy was 2.4%, 6.0% and 22.5% in patients with low (60%), intermediate (21%) and high (19%) genomic classifier scores, respectively (p<0.001). CONCLUSIONS Results indicate that genomic information from the primary tumor can identify patients with adverse pathological features who are most at risk for metastasis and potentially lethal prostate cancer.
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17
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Karon BS, Boyd JC, Klee GG. Empiric validation of simulation models for estimating glucose meter performance criteria for moderate levels of glycemic control. Diabetes Technol Ther 2013; 15:996-1003. [PMID: 24032487 DOI: 10.1089/dia.2013.0086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND We used simulation modeling to relate glucose meter performance criteria to insulin dosing errors for patients on a moderate glycemic control protocol (glucose target, 110-150 mg/dL) and empirically validated assumptions from simulation models using observed glucose meter and laboratory glucose values obtained nearly simultaneously. SUBJECTS AND METHODS The 25,948 glucose values from 1,513 patients on a moderate glycemic control protocol were used to represent the expected distribution of glucose values in this patient population. Simulation models were used to relate glucose meter analytical performance to insulin dosing errors assuming 10%, 15%, or 20% total allowable error (TEa). In addition, 4,017 paired glucose meter and serum laboratory glucose measurements drawn within 5 min of each other were used to generate an empiric dataset to validate simulation model assumptions relating glucose meter performance to insulin dosing errors. RESULTS Large (three or more category) insulin dosing errors are predicted to occur only under the 20% TEa condition. Two category insulin dosing errors were common (6-20% of all insulin dosing decisions) when 20% TEa was assumed, but frequency decreased to only 0.2% of dosing decisions when 10% TEa was modeled. When insulin dosing error rates were measured empirically by comparing paired glucose meter and laboratory glucose values, insulin dosing error rates were very similar to those predicted for the 20% TEa condition. CONCLUSIONS Both simulation models and empiric data demonstrate that glucose meters that perform at ≥20% TEa allow large insulin dosing errors during a moderate glycemic control protocol.
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Affiliation(s)
- Brad S Karon
- 1 Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota
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18
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Sarma AV, St Sauver JL, Jacobson DJ, McGree ME, Klee GG, Lieber MM, Girman CJ, Hollingsworth JM, Jacobsen SJ. Racial differences in longitudinal changes in serum prostate-specific antigen levels: the Olmsted County Study and the Flint Men's Health Study. Urology 2013; 83:88-93. [PMID: 24139354 DOI: 10.1016/j.urology.2013.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 07/25/2013] [Accepted: 08/12/2013] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To determine the distribution of, and racial differences in, changes in prostate-specific antigen (PSA) from a population-based sample of men. MATERIALS AND METHODS Data from 2 prospective cohort studies of a random sample of white men, aged 40-79 years in 1990, followed biennially through 2007, and African American men, aged 40-79 years in 1996, followed through 2000, were examined to assess the longitudinal changes in PSA concentrations. Serum PSA levels were determined at each examination for both cohorts and observations after a diagnosis of prostate cancer or treatment of benign prostatic hyperplasia were censored. The observed and estimated annual percentage of change in the serum PSA levels were examined by race. RESULTS At baseline, the median PSA level in the white men did not differ from the median level observed in the African American men (white men 0.9 ng/mL; African American men 0.9 ng/mL; P = .48). However, African American men had a much more rapid increase in the PSA level over time compared with the white men (median annual percent change in PSA for white men 3.6%/y, African American men 7.9%/y; P <.001). CONCLUSION These data suggest that African American men have more rapid rates of change in the PSA levels over time. If the difference in the rate of changes between African American and white men is an early indicator of future prostate cancer diagnosis, earlier detection in African American men could help to alleviate the racial disparities in prostate cancer diagnosis and mortality.
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Affiliation(s)
- Aruna V Sarma
- Department of Urology, University of Michigan, Ann Arbor, MI.
| | | | - Debra J Jacobson
- Division of Biomedical Statistics and Informatics, Mayo Clinic College of Medicine, Rochester, MN
| | - Michaela E McGree
- Division of Biomedical Statistics and Informatics, Mayo Clinic College of Medicine, Rochester, MN
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, MN
| | - Michael M Lieber
- Department of Urology, Mayo Clinic College of Medicine, Rochester, MN
| | - Cynthia J Girman
- Comparative and Outcomes Evidence Unit, Merck Research Laboratories, Blue Bell, PA
| | | | - Steven J Jacobsen
- Department of Research and Evaluation, Kaiser Permanente, Southern California, Pasadena, CA
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Ramamohan V, Yih Y, Abbott JT, Klee GG. Category-specific uncertainty modeling in clinical laboratory measurement processes. Clin Chem Lab Med 2013; 51:2273-80. [PMID: 23969469 DOI: 10.1515/cclm-2013-0357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/23/2013] [Indexed: 11/15/2022]
Abstract
BACKGROUND A statement of measurement uncertainty describes the quality of a clinical assay analysis result, and uncertainty models of clinical assays can be used to evaluate and optimize laboratory protocols designed to minimize the measurement uncertainty associated with an assay. In this study, we propose a methodology to lend systematic structure to the uncertainty modeling process. METHODS Clinical laboratory assays are typically classified based on the chemical reaction involved, and therefore, based on the assay analysis methodology. We use this fact to demonstrate that uncertainty models for assays within the same category are structurally identical in all respects except for the values of certain model parameters. This is accomplished by building uncertainty models for assays belonging to two categories--substrate assays based on optical absorbance analysis of endpoint reactions, and ion selective electrode (ISE) assays based on potentiometric measurements of electromotive force. RESULTS Uncertainty models for the substrate assays and the ISE assays are built, and for each category, a general mathematical framework for the uncertainty model is developed. The parameters of the general framework that vary from assay to assay for each category are identified and listed. CONCLUSIONS Estimates of measurement uncertainty from the models were compared with estimates of uncertainty from quality control data from the clinical laboratory. We demonstrate that building a general modeling framework for each assay category and plugging in parameter values for each assay is sufficient to generate uncertainty models for an assay within a given category.
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20
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Ye Z, Ali Z, Klee GG, Mosley TH, Kullo IJ. Associations of candidate biomarkers of vascular disease with the ankle-brachial index and peripheral arterial disease. Am J Hypertens 2013; 26:495-502. [PMID: 23467205 DOI: 10.1093/ajh/hps073] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The use of multiple biomarkers representing various etiologic pathways of atherosclerosis may improve the prediction of interindividual variation in the ankle-brachial index (ABI). To this end, we investigated associations of 47 candidate biomarkers with the ABI and presence of peripheral arterial disease (PAD) in African-Americans (AAs) and non-Hispanic whites (NHWs). METHODS Study participants included 1,291 AAs (71.1% women, mean age, 63.4±9.3 years) and 1,152 NHWs (57.5% women, mean age 58.5±10.1 years) belonging to hypertensive sibships. Peripheral arterial disease was defined as an ABI ≤ 0.90. Circulating levels of 47 candidate biomarkers were log-transformed before analysis because of skewed distribution. Multivariate regression analyses were used to identify biomarkers associated with ABI or PAD independently of age, sex, conventional risk factors, and medication use. RESULTS After adjustment for covariates, higher levels of nine biomarkers were associated with a lower ABI in AAs (all P ≤ 0.005); these biomarkers were C-reactive protein (CRP), interleukin-6, tumor necrosis factor receptor-II (TNF-R II), lipoprotein(a), N-terminal pro-brain natriuretic peptide (NT-proBNP), pro-atrial natriuretic peptide, C-terminal pro-arginine vasopressin, osteoprotegerin, and fibrinogen. Three biomarkers - myeloperoxidase, NT-proBNP, and D-dimer - were associated with ABI in NHWs (all P ≤ 0.01). C-reactive protein, interleukin-6, TNF-R II, lipoprotein(a), NT-proBNP, pro-atrial natriuretic peptide, D-dimer, and fibrinogen were associated with PAD (all P ≤ 0.005) in AAs after adjustment for covariates. None of the biomarkers were independently associated with PAD in NHWs. CONCLUSION A multimarker approach improved the prediction of interindividual variation in the ABI in AAs and NHWs, and improved prediction of the presence of PAD in AAs.
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Affiliation(s)
- Zi Ye
- Division of Cardiovascular Diseases and the Gonda Vascular Center, Mayo Clinic, Rochester, MN, USA
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21
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Aggarwal G, Ramachandran V, Javeed N, Arumugam T, Dutta S, Klee GG, Klee EW, Smyrk TC, Bamlet W, Han JJ, Rumie Vittar NB, De Andrade M, Mukhopadhyay D, Petersen GM, Fernandez-Zapico ME, Logsdon CD, Chari ST. Adrenomedullin is up-regulated in patients with pancreatic cancer and causes insulin resistance in β cells and mice. Gastroenterology 2012; 143:1510-1517.e1. [PMID: 22960655 PMCID: PMC3787599 DOI: 10.1053/j.gastro.2012.08.044] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 08/14/2012] [Accepted: 08/30/2012] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS New-onset diabetes in patients with pancreatic cancer is likely to be a paraneoplastic phenomenon caused by tumor-secreted products. We aimed to identify the diabetogenic secretory product(s) of pancreatic cancer. METHODS Using microarray analysis, we identified adrenomedullin as a potential mediator of diabetes in patients with pancreatic cancer. Adrenomedullin was up-regulated in pancreatic cancer cell lines, in which supernatants reduced insulin signaling in beta cell lines. We performed quantitative reverse-transcriptase polymerase chain reaction and immunohistochemistry on human pancreatic cancer and healthy pancreatic tissues (controls) to determine expression of adrenomedullin messenger RNA and protein, respectively. We studied the effects of adrenomedullin on insulin secretion by beta cell lines and whole islets from mice and on glucose tolerance in pancreatic xenografts in mice. We measured plasma levels of adrenomedullin in patients with pancreatic cancer, patients with type 2 diabetes mellitus, and individuals with normal fasting glucose levels (controls). RESULTS Levels of adrenomedullin messenger RNA and protein were increased in human pancreatic cancer samples compared with controls. Adrenomedullin and conditioned media from pancreatic cell lines inhibited glucose-stimulated insulin secretion from beta cell lines and islets isolated from mice; the effects of conditioned media from pancreatic cancer cells were reduced by small hairpin RNA-mediated knockdown of adrenomedullin. Conversely, overexpression of adrenomedullin in mice with pancreatic cancer led to glucose intolerance. Mean plasma levels of adrenomedullin (femtomoles per liter) were higher in patients with pancreatic cancer compared with patients with diabetes or controls. Levels of adrenomedullin were higher in patients with pancreatic cancer who developed diabetes compared those who did not. CONCLUSIONS Adrenomedullin is up-regulated in patients with pancreatic cancer and causes insulin resistance in β cells and mice.
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Affiliation(s)
- Gaurav Aggarwal
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | - Naureen Javeed
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | - Shamit Dutta
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - George G. Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Eric W. Klee
- Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Thomas C. Smyrk
- Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - William Bamlet
- Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Jing Jing Han
- Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Natalia B. Rumie Vittar
- Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Mariza De Andrade
- Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Debabrata Mukhopadhyay
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Gloria M. Petersen
- Department of Health Sciences Research, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Martin E. Fernandez-Zapico
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota,Schulze Center for Novel Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Craig D. Logsdon
- Department of Cancer Biology, UT MD Anderson Cancer Center, Houston, Texas
| | - Suresh T. Chari
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota
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22
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Loeb S, Sokoll LJ, Broyles DL, Bangma CH, van Schaik RHN, Klee GG, Wei JT, Sanda MG, Partin AW, Slawin KM, Marks LS, Mizrahi IA, Shin SS, Cruz AB, Chan DW, Roberts WL, Catalona WJ. Prospective multicenter evaluation of the Beckman Coulter Prostate Health Index using WHO calibration. J Urol 2012. [PMID: 23206426 DOI: 10.1016/j.juro.2012.11.149] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE Reported prostate specific antigen values may differ substantially among assays using Hybritech® or WHO standardization. The Beckman Coulter® Prostate Health Index and [-2]proPSA are newly approved serum markers associated with prostate cancer risk and aggressiveness. We studied the influence of assay standardization on these markers. MATERIALS AND METHODS Prostate specific antigen, percent free prostate specific antigen and [-2]proPSA were measured using Hybritech calibration in 892 men from a prospective, multicenter study undergoing prostate biopsy. We calculated the Prostate Health Index using the equation, ([-2]proPSA/free prostate specific antigen) × PSA. Index performance characteristics for prostate cancer detection were then determined using recalculated WHO calibration prostate specific antigen values. RESULTS The median Prostate Health Index was significantly higher in men with prostate cancer than in those with negative biopsies using WHO values (47.4 vs 39.8, p <0.001). The index offered improved discrimination of prostate cancer detection on biopsy (AUC 0.704) compared to percent free or total prostate specific antigen using the WHO calibration. CONCLUSIONS The Prostate Health Index can be calculated using Hybritech or WHO standardized assays. It significantly improved prediction of the biopsy outcome over that of percent free or prostate specific antigen alone.
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Affiliation(s)
- Stacy Loeb
- Department of Urology, New York University Langone Medical Center, New York, New York, USA
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Mahapatra S, Klee EW, Young CYF, Sun Z, Jimenez RE, Klee GG, Tindall DJ, Donkena KV. Global methylation profiling for risk prediction of prostate cancer. Clin Cancer Res 2012; 18:2882-95. [PMID: 22589488 DOI: 10.1158/1078-0432.ccr-11-2090] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The aim of this study was to investigate the promoter hypermethylation as diagnostic markers to detect malignant prostate cells and as prognostic markers to predict the clinical recurrence of prostate cancer. EXPERIMENTAL DESIGN DNA was isolated from prostate cancer and normal adjacent tissues. After bisulfite conversion, methylation of 14,495 genes was evaluated using the Methylation27 microarrays in 238 prostate tissues. We analyzed methylation profiles in four different groups: (i) tumor (n = 198) versus matched normal tissues (n = 40), (ii) recurrence (n = 123) versus nonrecurrence (n = 75), (iii) clinical recurrence (n = 80) versus biochemical recurrence (n = 43), and (iv) systemic recurrence (n = 36) versus local recurrence (n = 44). Group 1, 2, 3, and 4 genes signifying biomarkers for diagnosis, prediction of recurrence, clinical recurrence, and systemic progression were determined. Univariate and multivariate analyses were conducted to predict risk of recurrence. We validated the methylation of genes in 20 independent tissues representing each group by pyrosequencing. RESULTS Microarray analysis revealed significant methylation of genes in four different groups of prostate cancer tissues. The sensitivity and specificity of methylation for 25 genes from 1, 2, and 4 groups and 7 from group 3 were shown. Validation of genes by pyrosequencing from group 1 (GSTP1, HIF3A, HAAO, and RARβ), group 2 (CRIP1, FLNC, RASGRF2, RUNX3, and HS3ST2), group 3 (PHLDA3, RASGRF2, and TNFRSF10D), and group 4 (BCL11B, POU3F3, and RASGRF2) confirmed the microarray results. CONCLUSIONS Our study provides a global assessment of DNA methylation in prostate cancer and identifies the significance of genes as diagnostic and progression biomarkers of prostate cancer.
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Affiliation(s)
- Saswati Mahapatra
- Department of Urology and Laboratory Medicine and Pathology, Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota 55905, USA
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Ramamohan V, Abbott J, Klee GG, Yih Y. Application of mathematical models of system uncertainty to evaluate the utility of assay calibration protocols. Clin Chem Lab Med 2012; 50:1945-51. [PMID: 23093083 DOI: 10.1515/cclm-2012-0265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 05/24/2012] [Indexed: 11/15/2022]
Abstract
BACKGROUND Laboratory protocols used to calibrate commercial clinical chemistry systems affect test result quality. Mathematical models of system uncertainty can be developed using performance parameters provided by the manufacturer for various subsystems. These models can be used to evaluate protocols for specific laboratory operations. METHODS A mathematical model was developed to estimate the uncertainty inherent in the Roche Diagnostics P-Modular system, and included uncertainties associated with the sample and reagent pipettes, spectrometer and the calibration process. The model was then used to evaluate various alternate calibration protocols: calibration based on mean of replicate measurements (n=1-6) and calibration based on conditional acceptance when the following quality control specimen was within one standard deviation of target. The effect of calibrator concentrations on assay measurement uncertainty was also studied, and calibrator concentrations that minimize uncertainty at a specific concentration were identified. RESULTS The simulation model produced uncertainty estimates of 3.5% for the serum cholesterol assay and identified sample pipette (40%) and spectrometer (21%) as the largest contributors to measurement uncertainty. Each additional replicate calibrator measurements result in diminishing reductions in measurement uncertainty, with maximum reductions (19%) achieved with five replicate measurements. The conditional acceptance of calibration only when the control was within 1s resulted in an 18% reduction. CONCLUSIONS The model can be used to evaluate the utility of laboratory protocols and establish realistic assay performance targets. The model also can help instrument manufacturers and laboratorians identify major contributors to assay measurement uncertainty, which helps improve performance in future assay systems.
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Affiliation(s)
- Varun Ramamohan
- School of Industrial Engineering, Purdue University, West Lafayette, IN, USA.
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Buerki C, Mitra AP, Black PC, Ghadessi M, Bergstralh EJ, Erho N, Carlson R, Crisan A, Sierocinski T, Zimmermann B, Haddad Z, Vergara IA, Ballman KV, Klee GG, Fink S, Kollmeyer TM, Triche TJ, Davicioni E, Karnes RJ, Jenkins RB. Validation of a genomic-clinical classifier for predicting clinical progression in high-risk prostate cancer. J Clin Oncol 2012. [DOI: 10.1200/jco.2012.30.15_suppl.4565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
4565 Background: The efficient delivery of adjuvant therapy after radical prostatectomy (RP) in patients with prostate cancer is limited by the lack of biomarkers, beyond clinicopathologic factors, that are able to assess the risk of clinically significant disease progression. Previously, routine FFPE patient specimens from the Mayo Clinic Radical Prostatectomy Registry with long term follow-up were selected to develop a genomic classifier (GC) to predict clinical progression. Here, we present the validation of a GC in a cohort of patients at high risk of disease progression. Methods: A case-cohort study of high-risk RP patients from the Mayo Clinic (N=219) was used to validate the genomic classifier (GC) for predicting clinical progression (defined by positive bone or CT scan post-RP). Its performance was compared to a multivariable clinical classifier (CC) and a genomic-clinical classifier (GCC) which combines GC with established clinicopathologic variables. Concordance index, Cox modeling and decision curve analysis were used to compare the different models. Results: GC and GCC were predictive of clinical progression in the high-risk cohort with c-indices of 0.79 and 0.82, respectively, compared to the clinical classifier (0.70). Multivariable survival analysis showed that the majority of prognostic information of GCC came from the GC with a minor contribution from Gleason score. Decision curve analysis showed that GCC had a higher overall net benefit compared to CC over a wide range of ‘decision-to-treat’ thresholds for the risk of progression. Conclusions: In this high-risk cohort, GC and GCC classifiers showed improved performance over CC in prediction of clinical progression. GC is an independent prognostic factor in this cohort and captures the majority of prognostic information. GC and GCC’s prognostic performance and their usefulness in guiding decision-making in the adjuvant setting after RP need further testing in studies of additional prostate cancer risk groups.
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Affiliation(s)
| | - Anirban Pradip Mitra
- University of Southern California Keck School of Medicine and Norris Comprehensive Cancer Center, Los Angeles, CA
| | - Peter C. Black
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | | | | | | | - Rachel Carlson
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | | | | | | | - Zaid Haddad
- GenomeDx Biosciences Inc., Vancouver, BC, Canada
| | | | - Karla V. Ballman
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - George G. Klee
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - Stephanie Fink
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | | | | | | | - Robert B. Jenkins
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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Rhodes T, Jacobson DJ, McGree ME, St Sauver JL, Girman CJ, Lieber MM, Klee GG, Demissie K, Jacobsen SJ. Longitudinal changes of benign prostate-specific antigen and [-2]proprostate-specific antigen in seven years in a community-based sample of men. Urology 2012; 79:655-61. [PMID: 22386420 DOI: 10.1016/j.urology.2011.09.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/23/2011] [Accepted: 09/28/2011] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To determine the longitudinal changes of benign prostate-specific antigen (BPSA) and [-2]proPSA and how these changes relate to the outcomes. These markers have been shown to be predictive of prostate cancer (CaP) and benign prostatic hyperplasia treatment; however, little is known about longitudinal changes in these markers. METHODS In 1990, a 25% subsample from a cohort of white men aged 40-79 years, who were randomly selected from Olmsted County, Minnesota residents, completed a detailed clinical examination. BPSA and [-2]proPSA were measured from frozen sera. The men were evaluated biennially (median follow-up 7 years; range 0-8.8). Mixed-effects regression models were used to estimate the longitudinal changes in the BPSA and [-2]proPSA levels overall and by outcomes. Spearman correlations were used to compare these changes with the baseline levels and the annualized changes in urologic measures. RESULTS The median and 25th and 75th percentiles annualized percent change for [-2]proPSA and BPSA was 3.7%, 2.5% and 5.2% and 7.3%, 6.8%, and 7.7%, respectively. The annualized percent change for both markers correlated with the baseline and annualized changes in PSA and prostate volume. The annualized percent change increased with increasing age decade for [-2]proPSA but not for BPSA. The rate of increase in [-2]proPSA was significantly greater for men who developed enlarged prostates (median 3.5%, 25th and 75th percentile 2.6% and 4.4%, respectively) or CaP (median 8.1%, 25th and 75th percentile 6.6% and 9.8%, respectively) compared with those who did not develop enlarged prostates (median 1.9%, 25th and 75th percentile 0.9% and 3.0%, respectively) or CaP (median 3.5%, 25th and 75th percentile 2.3% and 4.8%, respectively). CONCLUSION BPSA and [-2]proPSA levels increase over time. The annualized percent change in [-2]proPSA increases with age and might be a useful predictor of CaP development.
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Affiliation(s)
- Thomas Rhodes
- Department of Epidemiology, University of Medicine and Dentistry in New Jersey, Piscataway, New Jersey, USA
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27
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Sokoll LJ, Chan DW, Klee GG, Roberts WL, van Schaik RHN, Arockiasamy DA, Broyles DL, Carlson CM, Mizrahi IA, Pierson TB, Tam JE. Multi-center analytical performance evaluation of the Access Hybritech® p2PSA immunoassay. Clin Chim Acta 2012; 413:1279-83. [PMID: 22542565 DOI: 10.1016/j.cca.2012.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 01/13/2023]
Abstract
BACKGROUND Total PSA assays measure both complexed and non-complexed forms of PSA while free PSA assays only measure non-complexed forms. Free PSA is a mixture of isoforms including immature PSA (proPSA) with retained portions of the leader sequence (e.g. [-7], [-4], and [-2]proPSA) and nicked forms (BPSA). ProPSA isoforms in male sera have been associated with prostate cancer. This study characterized the analytical performance of a chemiluminescent immunoassay for [-2]proPSA. METHODS The Access Hybritech p2PSA assay is a sandwich immunoassay using an anti-[-2]proPSA monoclonal antibody attached to paramagnetic beads and an anti-PSA monoclonal antibody conjugated to alkaline phosphatase calibrated with recombinant [-2]proPSA. Analytical studies including sensitivity (CLSI EP17-A) and imprecision (CLSI EP5-A2) were performed. RESULTS The Access Hybritech p2PSA assay for [-2]proPSA had a dynamic range of 0.5 to 5000 pg/ml. The total CV of the assay was <7% for [-2]proPSA concentrations between 20 and 1000 pg/ml. The LOB was 0.50 pg/ml, LOD 0.69 pg/ml, and LOQ 3.23 pg/ml (20% CV). There was no hook effect up to 15,000 pg/ml. There was a <5% difference between calibrator and reagent lots and no interference from normal serum constituents. CONCLUSIONS The Access Hybritech p2PSA assay is a robust immunoassay for the measurement of serum [-2]proPSA.
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Affiliation(s)
- Lori J Sokoll
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, MD 21287, United States
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28
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Klee EW, Bondar OP, Goodmanson MK, Dyer RB, Erdogan S, Bergstralh EJ, Bergen HR, Sebo TJ, Klee GG. Candidate serum biomarkers for prostate adenocarcinoma identified by mRNA differences in prostate tissue and verified with protein measurements in tissue and blood. Clin Chem 2012; 58:599-609. [PMID: 22247499 PMCID: PMC3951013 DOI: 10.1373/clinchem.2011.171637] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Improved tests are needed for detection and management of prostate cancer. We hypothesized that differential gene expression in prostate tissue could help identify candidate blood biomarkers for prostate cancer and that blood from men with advanced prostate disease could be used to verify the biomarkers presence in circulation. METHODS We identified candidate markers using mRNA expression patterns from laser-capture microdissected prostate tissue and confirmed tissue expression using immunohistochemistry (IHC) for the subset of candidates having commercial antisera. We analyzed tissue extracts with tandem mass spectrometry (MS/MS) and measured blood concentrations using immunoassays and MS/MS of trypsin-digested, immunoextracted peptides. RESULTS We selected 35 novel candidate prostate adenocarcinoma biomarkers. For all 13 markers having commercial antisera for IHC, tissue expression was confirmed; 6 showed statistical discrimination between nondiseased and malignant tissue, and only 5 were detected in tissue extracts by MS/MS. Sixteen of the 35 candidate markers were successfully assayed in blood. Four of 8 biomarkers measured by ELISA and 3 of 10 measured by targeted MS showed statistically significant increases in blood concentrations of advanced prostate cancer cases, compared with controls. CONCLUSIONS Seven novel biomarkers identified by gene expression profiles in prostate tissue were shown to have statistically significant increased concentrations in blood from men with advanced prostate adenocarcinoma compared with controls: apolipoprotein C1, asporin, cartilage oligomeric matrix protein, chemokine (C-X-C motif) ligand 11 (CXCL11), CXCL9, coagulation factor V, and proprotein convertase subtilisin/kexin 6.
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Affiliation(s)
- Eric W. Klee
- Department of Health Sciences Research, Mayo Clinic Rochester
| | - Olga P. Bondar
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester
| | | | - Roy B. Dyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester
| | - Sibel Erdogan
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester
| | | | - H. Robert Bergen
- Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester
| | - Thomas J. Sebo
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester
| | - George G. Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester
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Jenkins RB, Bergstralh EJ, Davicioni E, Karnes RJ, Ballman KV, Fink S, Black PC, Ghadessi M, Triche TJ, Klee GG, Kollmeyer TM, Vergara IA, Crisan A, Erho N, Sierocinski T, Buerki C, Carlson R, Grill DE, Zimmermann B, Haddad Z. Validation of a genomic-clinical classifier model for predicting clinical recurrence of patients with localized prostate cancer in a high-risk population. J Clin Oncol 2012. [DOI: 10.1200/jco.2012.30.5_suppl.175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
175 Background: The efficient delivery of adjuvant and salvage therapy after radical prostatectomy in patients with prostate cancer is hampered by a lack of biomarkers to assess the risk of clinically significant recurrence and progression. Methods: Mayo Clinic Radical Prostatectomy Registry (RP) patient specimens were selected from a case-control cohort with 14 years median follow-up for training and initial validation of an expression biomarker genomic classifier (GC). An independent, blinded case-cohort study of high-risk RP subjects was used to validate GC, comparing the performance of GC to a multivariate logistic regression clinical model (CM) and GC combined with clinical variables (genomic-clinical classifier, GCC) for predicting clinical recurrence (defined as positive bone or CT scan within 5 years after biochemical recurrence). The concordance index (c-index) and Cox model were used to evaluate discrimination and estimate the risk of clinical recurrence. Results: In the training subset (n=359), both GC and GCC had a c-index of 0.90 whereas CM had a c-index of 0.76. In the internal validation set (n=186), GC and GCC had a c-index of 0.76 and 0.75, while CM had a c-index of 0.69. In an independent high-risk study (n=219), GC and GCC had a c-index of 0.77 and 0.76, while CM had a c-index of 0.68. In subset analysis of Gleason score 7 patients within the high-risk group, GC and GCC showed improved discrimination with c-index of 0.78 and 0.76, respectively compared to 0.70 for CM. In the high-risk group, the risk of recurrence by GC model score quartiles at 5 years after RP was estimated at 1%, 5%, 5% and 18%. Conclusions: The GC model shows improved performance over CM in the prediction of clinical recurrence in a high-risk cohort and in subset analysis of Gleason score 7 patients. The addition of clinical variables to the GC model did not significantly contribute to classifier performance in patients with high-risk features. We are further testing the performance of the GC and GCC models and their usefulness in guiding decision-making (e.g., for the adjuvant therapy setting) in additional studies of prostate cancer clinical risk groups.
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Affiliation(s)
- Robert B. Jenkins
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Eric J Bergstralh
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Elai Davicioni
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - R. Jeffrey Karnes
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Karla V. Ballman
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Stephanie Fink
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Peter C. Black
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Mercedeh Ghadessi
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Timothy J. Triche
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - George G Klee
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Thomas M. Kollmeyer
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Ismael A Vergara
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Anamaria Crisan
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Nicholas Erho
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Thomas Sierocinski
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Christine Buerki
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Rachel Carlson
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Diane E Grill
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Benedikt Zimmermann
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
| | - Zaid Haddad
- Mayo Clinic, Rochester, MN; GenomeDx Biosciences Inc., Vancouver, BC, Canada; University of British Columbia, Vancouver, BC, Canada; Gen, Vancouver, BC, Canada; G, Vancouver, BC, Canada
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Jacobsen SJ, Jacobson DJ, McGree ME, St. Sauver JL, Klee GG, Girman CJ, Lieber MM. Sixteen-year longitudinal changes in serum prostate-specific antigen levels: the olmsted county study. Mayo Clin Proc 2012; 87:34-40. [PMID: 22212966 PMCID: PMC3538390 DOI: 10.1016/j.mayocp.2011.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 08/22/2011] [Accepted: 09/06/2011] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To determine the distribution of longitudinal changes in serum prostate-specific antigen (PSA) levels from a population-based sample of men. PATIENTS AND METHODS In this prospective cohort study, a random sample of Olmsted County, Minnesota, men aged 40 to 79 years in 1990 were followed up biennially from January 1, 1990, through August 29, 2007. Serum PSA levels were determined at each examination, and men were censored for follow-up with a diagnosis of prostate cancer or treatment for benign prostatic hyperplasia. The empirical distributions of annual percent change and annual absolute change in serum PSA level were calculated and tabulated, including the median and 75th and 95th percentiles. RESULTS For men with PSA measurements 2 years apart, the median annual percent change in serum PSA level was 4.83% and the 95th percentile was about 49.76%. The variability in estimated annual change decreased with increasing time between assessments, with a 95th percentile of 21.82% after 8 or more years between assessments. Although the median absolute change per year increased with increasing age, the median percent change per year was fairly consistent across age groups. CONCLUSION These data demonstrate that, with shorter intervals between assessments, greater variability should be expected. These distributions should prove helpful to patients and clinicians in interpreting changes in serum PSA levels observed in typical clinical practices.
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Affiliation(s)
- Steven J. Jacobsen
- Department of Research and Evaluation, Southern California Permanente Medical Group, Pasadena, CA
| | - Debra J. Jacobson
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN
| | - Michaela E. McGree
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN
| | - Jennifer L. St. Sauver
- Division of Epidemiology, Mayo Clinic, Rochester, MN
- Correspondence: Address to Jennifer L. St. Sauver, PhD, Division of Epidemiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905
| | - George G. Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Cynthia J. Girman
- Division of Epidemiology, Mayo Clinic, Rochester, MN
- Merck Research Laboratories, Blue Bell, PA
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Ramamohan V, Chandrasekar V, Abbott J, Klee GG, Yih Y. A Monte Carlo approach to the estimation & analysis of uncertainty in clinical laboratory measurement processes. ACTA ACUST UNITED AC 2012. [DOI: 10.1080/19488300.2012.665153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Rhodes T, Jacobson DJ, McGree ME, St Sauver JL, Sarma AV, Girman CJ, Lieber MM, Klee GG, Demissie K, Jacobsen SJ. Benign prostate specific antigen distribution and associations with urological outcomes in community dwelling black and white men. J Urol 2011; 187:87-91. [PMID: 22093190 DOI: 10.1016/j.juro.2011.09.061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Indexed: 01/25/2023]
Abstract
PURPOSE We describe cross-sectional associations of benign prostate specific antigen with clinical urological measures and examined the risk of future urological outcomes in 2 population based cohorts of black and white men, respectively. MATERIALS AND METHODS Two population based cohort studies were established to characterize the natural history of and risk factors for prostate disease progression in white and black male residents of Olmsted County, Minnesota, and Genesee County, Michigan, respectively. RESULTS The benign prostate specific antigen distribution was similar in black men at a median of 32.9 pg/ml (25th, 75th percentiles 17.3, 68.0) and white men at a median of 32.2 pg/ml (25th, 75th percentiles 16.6, 68.9, respectively). However, it was much lower than in previous reports. For Olmsted County men in the upper quartile of benign prostate specific antigen there was a fifteenfold increased risk of prostate cancer (HR 14.6, 95% CI 3.1-68.6) and a twofold higher risk of treatment for benign prostatic hyperplasia (HR 2.2, 95% CI 1.2-4.2) after adjusting for age. After additional adjustment for baseline prostate specific antigen the association between benign prostate specific antigen and prostate cancer risk was attenuated but remained almost ninefold higher for men in the upper quartile of benign prostate specific antigen (HR 8.7, 95% CI 1.8-42.4). The twofold higher risk of treatment for benign prostatic hyperplasia also remained after adjusting for baseline prostate specific antigen for men in the upper benign prostate specific antigen quartile (HR 1.9, 95% CI 0.9-4.0). CONCLUSIONS Results suggest that increased benign prostate specific antigen may help identify men with prostate cancer and those at risk for benign prostatic hyperplasia treatment.
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Affiliation(s)
- Thomas Rhodes
- Department of Epidemiology, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, USA
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Catalona WJ, Partin AW, Sanda MG, Wei JT, Klee GG, Bangma CH, Slawin KM, Marks LS, Loeb S, Broyles DL, Shin SS, Cruz AB, Chan DW, Sokoll LJ, Roberts WL, van Schaik RHN, Mizrahi IA. A multicenter study of [-2]pro-prostate specific antigen combined with prostate specific antigen and free prostate specific antigen for prostate cancer detection in the 2.0 to 10.0 ng/ml prostate specific antigen range. J Urol 2011; 185:1650-5. [PMID: 21419439 PMCID: PMC3140702 DOI: 10.1016/j.juro.2010.12.032] [Citation(s) in RCA: 318] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Indexed: 01/12/2023]
Abstract
PURPOSE Prostate specific antigen and free prostate specific antigen have limited specificity to detect clinically significant, curable prostate cancer, leading to unnecessary biopsy, and detection and treatment of some indolent tumors. Specificity to detect clinically significant prostate cancer may be improved by [-2]pro-prostate specific antigen. We evaluated [-2]pro-prostate specific antigen, free prostate specific antigen and prostate specific antigen using the formula, ([-2]pro-prostate specific antigen/free prostate specific antigen × prostate specific antigen(1/2)) to enhance specificity to detect overall and high grade prostate cancer. MATERIALS AND METHODS We enrolled 892 men with no history of prostate cancer, normal rectal examination, prostate specific antigen 2 to 10 ng/ml and 6-core or greater prostate biopsy in a prospective multi-institutional trial. We examined the relationship of serum prostate specific antigen, free-to-total prostate specific antigen and the prostate health index with biopsy results. Primary end points were specificity and AUC using the prostate health index to detect overall and Gleason 7 or greater prostate cancer on biopsy compared with those of free-to-total prostate specific antigen. RESULTS In the 2 to 10 ng/ml prostate specific antigen range at 80% to 95% sensitivity the specificity and AUC (0.703) of the prostate health index exceeded those of prostate specific antigen and free-to-total prostate specific antigen. An increasing prostate health index was associated with a 4.7-fold increased risk of prostate cancer and a 1.61-fold increased risk of Gleason score greater than or equal to 4 + 3 = 7 disease on biopsy. The AUC of the index exceeded that of free-to-total prostate specific antigen (0.724 vs 0.670) to discriminate prostate cancer with Gleason 4 or greater + 3 from lower grade disease or negative biopsy. Prostate health index results were not associated with age and prostate volume. CONCLUSIONS The prostate health index may be useful in prostate cancer screening to decrease unnecessary biopsy in men 50 years old or older with prostate specific antigen 2 to 10 ng/ml and negative digital rectal examination with minimal loss in sensitivity.
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Affiliation(s)
- William J Catalona
- Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
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Donkena KV, Klee EW, Young CY, Klee GG, Tindall DJ, Blute ML. Abstract 109: DNA methylation profiling associated with recurrence of prostate cancer. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
DNA methylation profiles could signify the risk of prostate cancer and predict the progression of cancer before the appearance of clinical symptoms. Specific CpG sites methylation of genes identified in our study could be used to improve the sensitivity and specificity for early diagnosis and to predict the risk of prostate cancer recurrence. To identify methylation changes associated with prostate cancer, we measured gene methylation using the Infinium Human Methylation27 bead chips. Tissue DNA isolation and bisulfite conversion was done using ZR Genomic DNA kit and EZ methylation kit. The methylation27 microarrays was used to analyze methylation of 27,578 CpG sites of 14,495 genes in 198 tumor tissues and 40 matched normal tissues. Methylation data was processed using the Genome Studio software, differentially methylated genes identified using one-way analysis of variance, and correction for multiple testing done using the false discovery rate q-value. To identify putative diagnostic and prognostic biomarkers we performed four subgroup comparisons: tumor vs. matched normal, recurrent tumors vs. non-recurrent tumors, clinical recurrence vs. biochemical recurrence, and systemic recurrence vs. local recurrence. Clinicopathological and molecular features including patient preoperative PSA levels, Gelason score, TNM stage, GPSM, recurrence type, were also evaluated for subgroup discrimination. Discriminative subgroup candidate methlyation markers were selected using a p value <0.05 and a mean difference between two contrast groups >0.05. Between the tumor and matched normal tissue samples, 164 CpG sites representing 147 genes were identified as significantly differentially methylated (p<9.99E-25, fold change>2.0). Between recurrent tumor and non-recurrent tumor tissues there were 78 CpG sites representing 75 genes that were significantly differentially methylated (p <0.002, fold change >1.5). Between clinically recurrent and biochemically recurrent tumors, 16 CpG sites representing 16 genes were significantly differentially methylated (p <0.05, fold change >1.5). Between systemic recurrent and local recurrent tumors there were 73 CpG sites representing 68 genes that were significantly differentially methylated (p <0.01, fold change >1.5) Our analysis revealed differential methylation of the genes, implicating their role in prostate cancer development and progression. We demonstrated that the hypermethylation of genes could be used as a sensitive molecular tool in detection of prostate tumorigenesis and prediction of tumor progression.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 109. doi:10.1158/1538-7445.AM2011-109
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Catalona WJ, Sanda MG, Wei JT, Klee GG, Bangma CH, Slawin KM, Marks LS, Loeb S, Broyles DL, Shin SS, Cruz AB, Mizrahi IA, Chan DW, Sokoll LJ, Roberts WL, van Schaik RH, Partin AW. 982 EVALUATION OF THE PROSTATE HEALTH INDEX (
PHI
) IN THE 2 TO 4, AND 4 TO 10 NG/ML PSA RANGES: RESULTS FROM A MULTI-SITE, PROSPECTIVE, CLINICAL EVALUATION. J Urol 2011. [DOI: 10.1016/j.juro.2011.02.1014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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St Sauver JL, Jacobson DJ, McGree ME, Girman CJ, Klee GG, Lieber MM, Jacobsen SJ. Associations between longitudinal changes in serum estrogen, testosterone, and bioavailable testosterone and changes in benign urologic outcomes. Am J Epidemiol 2011; 173:787-96. [PMID: 21367876 DOI: 10.1093/aje/kwq438] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Some men have rapid increases in benign prostatic enlargement and lower urinary tract symptoms (LUTS), and it is not clear how sex steroid hormones contribute to the rates of change in these urologic outcomes. Therefore, the authors conducted a population-based cohort study of 648 men residing in Olmsted County, Minnesota, from 1990 to 2007, to examine associations between baseline sex steroid hormones, the rate of change in these hormones, and the rates of change in LUTS, maximum urinary flow rate, and prostate volume. Annual changes in hormone levels and urologic outcomes were calculated using mixed-effects regression models. Associations between hormone variables and rates of change in urologic outcomes were assessed with linear regression models. Higher baseline estradiol levels and rapid declines in estradiol over time were associated with rapid increases in LUTS and rapid decreases in maximum flow rate. Lower baseline bioavailable testosterone levels and more rapid declines in bioavailable testosterone were associated with more rapid increases in prostate volume. These results suggest that both absolute sex steroid hormone levels and the rates at which the levels change may be important in the development of urologic conditions in aging men.
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Affiliation(s)
- Jennifer L St Sauver
- Division of Epidemiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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Affiliation(s)
- Brad S Karon
- Department of Laboratory Medicine and Pathology Mayo Clinic Rochester, MN
| | - James C Boyd
- Department of Pathology University of Virginia Health System Charlottesville, VA
| | - George G Klee
- Department of Laboratory Medicine and Pathology Mayo Clinic Rochester, MN
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Abstract
Abstract
Background: Glucose meter analytical performance criteria required for safe and effective management of patients on tight glycemic control (TGC) are not currently defined. We used simulation modeling to relate glucose meter performance characteristics to insulin dosing errors during TGC.
Methods: We used 29 920 glucose values from patients on TGC at 1 institution to represent the expected distribution of glucose values during TGC, and we used 2 different simulation models to relate glucose meter analytical performance to insulin dosing error using these 29 920 initial glucose values and assuming 10%, 15%, or 20% total allowable error (TEa) criteria.
Results: One-category insulin dosing errors were common under all error conditions. Two-category insulin dosing errors occurred more frequently when either 20% or 15% TEa was assumed compared with 10% total error. Dosing errors of 3 or more categories, those most likely to result in hypoglycemia and thus patient harm, occurred infrequently under all error conditions with the exception of 20% TEa.
Conclusions: Glucose meter technologies that operate within a 15% total allowable error tolerance are unlikely to produce large (≥3-category) insulin dosing errors during TGC. Increasing performance to 10% TEa should reduce the frequency of 2-category insulin dosing errors, although additional studies are necessary to determine the clinical impact of such errors during TGC. Current criteria that allow 20% total allowable error in glucose meters may not be optimal for patient management during TGC.
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Affiliation(s)
- Brad S Karon
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - James C Boyd
- Department of Pathology, University of Virginia Health System, Charlottesville, VA
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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Affiliation(s)
- George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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Zhang J, Zhao D, Park HK, Wang H, Dyer RB, Liu W, Klee GG, McNiven MA, Tindall DJ, Molina JR, Fei P. FAVL elevation in human tumors disrupts Fanconi anemia pathway signaling and promotes genomic instability and tumor growth. J Clin Invest 2010; 120:1524-34. [PMID: 20407210 DOI: 10.1172/jci40908] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 02/17/2010] [Indexed: 12/22/2022] Open
Abstract
Fanconi anemia (FA) is a rare human genetic disease caused by mutations in any one of 13 known genes that encode proteins functioning in one common signaling pathway, the FA pathway, or in unknown genes. One characteristic of FA is an extremely high incidence of cancer, indicating the importance of the FA pathway in tumor suppression. However, the role of this pathway in the development and progression of human cancers in individuals who do not have FA has not been clearly determined. Here, we report that elevated expression of what we believe to be a novel splice variant of FA complementation group L (FANCL), which we identified and named FAVL, can impair the FA pathway in non-FA human tumor cells and act as a tumor promoting factor. FAVL expression was elevated in half of the human carcinoma cell lines and carcinoma tissue samples tested. Expression of FAVL resulted in decreased FANCL expression by sequestering FANCL to the cytoplasm and enhancing its degradation. Importantly, this impairment of the FA pathway by FAVL elevation provided human cancer cells with a growth advantage, caused chromosomal instability in vitro, and promoted tumor development in a xenograft mouse model. These data indicate that FAVL impairment of the FA pathway likely contributes to the development of non-FA human cancers and therefore add a challenging layer of complexity to the pathogenesis of human cancer. We further believe that these data will prove useful for developing additional tools for fighting human cancer.
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Affiliation(s)
- Jun Zhang
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Catalona WJ, Sanda MG, Wei JT, Klee GG, Slawin KM, Marks LS, Bangma CH, Chan DW, Sokoll LJ, Roberts WL, van Schaik R, Broyles DL, Cruz AB, Mizrahi IA, Shin SS, Partin AW. 1847 [-2]PROPSA IN COMBINATION WITH PSA AND FREE-PSA, USING THE BECKMAN COULTER ACCESS IMMUNOASSAY SYSTEMS IMPROVES PROSTATE CANCER DETECTION RELATIVE TO PSA AND FREE PSA. A MULTI-CENTER PROSPECTIVE CLINICAL STUDY. J Urol 2010. [DOI: 10.1016/j.juro.2010.02.1786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Catalona WJ, Sanda MG, Wei JT, Klee GG, Slawin KM, Marks LS, Bangma CH, Chan DW, Sokoll LJ, Roberts WL, van Schaik R, Broyles DL, Cruz AB, Le BV, Mizrahi IA, Shin SS, Partin AW. 137 EVALUATION OF [-2]PROPSA IN COMBINATION WITH PSA AND FREE PSA, USING THE BECKMAN COULTER ACCESS IMMUNOASSAY SYSTEMS, FOR IDENTIFYING PATIENTS WITH AGGRESSIVE PROSTATE CANCER. A MULTI-CENTER PROSPECTIVE CLINICAL EVALUATION. J Urol 2010. [DOI: 10.1016/j.juro.2010.02.189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
BACKGROUND Accrediting organizations require laboratories to establish analytic performance criteria that ensure their tests provide results of the high quality required for patient care. However, the procedures for instituting performance criteria that are directly linked to the needs of medical practice are not well established, and therefore alternative strategies often are used to create and implement surrogate performance standards. CONTENT We reviewed 6 approaches for establishing outcome-related analytic performance goals: (a) limits defined by regulations and external assessment programs, (b) limits based on biologic variation, (c) limits based on surveys of clinicians about their needs, (d) limits based on effects on guideline driven medical decisions, (e) limits based on analysis of patterns for ordering follow-up clinical tests, and (f) limits based on formal medical decision models. Performance criteria were tabulated for 12 common chemistry analytes and 4 routine hematology tests. CONCLUSIONS There is no consensus currently about the preferred methods for establishing medically necessary analytic performance limits. The various methods reviewed give considerably different performance limits. The analytic performance limits claimed by a laboratory should correspond to those limits that can be reliably maintained based on validated QC monitoring systems. These limits generally are larger than the observed CVs and bias parameters collected for assay validation. There is a major need for increased communication among laboratorians and clinicians on this topic, especially when the analytic performance limits that can be consistently maintained by a laboratory are inconsistent with the expectations of health care providers.
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Affiliation(s)
- George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
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Kim CX, Bailey KR, Klee GG, Ellington AA, Liu G, Mosley TH, Rehman H, Kullo IJ. Sex and ethnic differences in 47 candidate proteomic markers of cardiovascular disease: the Mayo Clinic proteomic markers of arteriosclerosis study. PLoS One 2010; 5:e9065. [PMID: 20140090 PMCID: PMC2816715 DOI: 10.1371/journal.pone.0009065] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 11/20/2009] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Cardiovascular disease (CVD) susceptibility differs between men and women and varies with ethnicity. This variability is not entirely explained by conventional CVD risk factors. We examined differences in circulating levels of 47 novel protein markers of CVD in 2561 men and women of African-American (AA) and non-Hispanic White (NHW) ethnicity, enrolled at geographically distinct sites. METHODOLOGY/PRINCIPAL FINDINGS Participants (1,324 AAs, mean age 63.5 y, 71% women; 1,237 NHWs, mean age 58.9 y, 57% women) belonged to sibships ascertained on the basis of hypertension. Solid-phase immunoassays and immunoturbidometric, clot-based, chromogenic, and electrophoretic assays were used to measure the 47 protein markers in plasma or serum. Marker levels were log transformed and outliers were adjusted to within 4 SD. To identify markers independently associated with sex or ethnicity, we employed multivariable regression analyses that adjusted for conventional risk factors, prior history of CVD, medication use and lifestyle factors (physical activity, alcohol consumption and education). Generalized estimating equations were used to correct for intrafamilial correlations. After adjustment for the above covariates, female sex was associated with higher levels of 29 markers and lower levels of 6 markers. Female sex was independently associated with higher levels of several inflammatory markers as well as lipoproteins, adipokines, natriuretic peptides, vasoconstrictor peptides and markers of calcification and thrombosis. AA ethnicity was associated with higher levels of 19 markers and lower levels of 6 markers, including higher levels of several inflammatory makers, higher leptin and lower adiponectin levels, lower levels of vasodilator-natriuretic peptides, higher levels of vasoconstrictor-antidiuretic peptides and markers of calcification and thrombosis. CONCLUSIONS/SIGNIFICANCE Plasma levels of several novel protein markers of CVD differ significantly in the context of sex and ethnicity. These results have implications for individualized CVD risk assessment.
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Affiliation(s)
- Charles X. Kim
- Mayo Clinic, Rochester, Minnesota, United States of America
| | - Kent R. Bailey
- Mayo Clinic, Rochester, Minnesota, United States of America
| | - George G. Klee
- Mayo Clinic, Rochester, Minnesota, United States of America
| | | | - Guanghui Liu
- Mayo Clinic, Rochester, Minnesota, United States of America
| | | | - Hamid Rehman
- Mayo Clinic, Rochester, Minnesota, United States of America
| | - Iftikhar J. Kullo
- Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
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Abstract
BACKGROUND The measurement of multiple protein biomarkers may refine risk stratification in clinical settings. This concept has stimulated development of multiplexed immunoassay platforms that provide multiple, parallel protein measurements on the same specimen. CONTENT We provide an overview of antibody-based multiplexed immunoassay platforms and discuss technical and operational challenges. Multiplexed immunoassays use traditional immunoassay principles in which high-affinity capture ligands are immobilized in parallel arrays in either planar format or on microspheres in suspension. Development of multiplexed immunoassays requires rigorous validation of assay configuration and analytical performance to minimize assay imprecision and inaccuracy. Challenges associated with multiplex configuration include selection and immobilization of capture ligands, calibration, interference between antibodies and proteins and assay diluents, and compatibility of assay limits of quantification. We discuss potential solutions to these challenges. Criteria for assessing analytical multiplex assay performance include the range of linearity, analytical specificity, recovery, and comparison to a quality reference method. Quality control materials are not well developed for multiplexed protein immunoassays, and algorithms for interpreting multiplex quality control data are needed. SUMMARY Technical and operational challenges have hindered implementation of multiplexed assays in clinical settings. Formal procedures that guide multiplex assay configuration, analytical validation, and quality control are needed before broad application of multiplexed arrays can occur in the in vitro diagnostic market.
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Affiliation(s)
- Allison A Ellington
- Division of Cardiovascular Diseases, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
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Abstract
BACKGROUND Multiplex arrays are increasingly used for measuring protein biomarkers. Advantages of this approach include specimen conservation, limited sample handling, and decreased time and cost, but the challenges of optimizing assay format for each protein, selecting common dilution factors, and establishing robust quality control algorithms are substantial. Here, we use measurements of 15 protein biomarkers from a large study to illustrate processing, analytic, and quality control issues with multiplexed immunoassays. METHODS We contracted with ThermoScientific for duplicate measurements of 15 proteins in 2322 participants from a community-based cohort, a plasma control, and recombinant protein controls using 2 custom planar microarrays with 6 (panel A) or 9 (panel B) capture antibodies printed in each well. We selected constituent analytes in each panel based on endogenous concentrations and assay availability. Protocols were standardized for sample processing, storage, and freeze-thaw exposures. We analyzed data for effects of deviations from processing protocols, precision, and bias. RESULTS Measurements were within reportable ranges for each of the assays; however, concentrations for 7 of the 15 proteins were not centered on the dose-response curves. An additional freeze-thaw cycle and erroneous sample dilution for a subset of samples produced significantly different results. Measurements with large differences between duplicates were seen to cluster by analyte, plate, and participant. Conventional univariate quality control algorithms rejected many plates. Plate-specific medians of cohort and plasma control data significantly covaried, an observation important for development of alternative quality control algorithms. CONCLUSIONS Multiplex measurements present difficult challenges that require further analytical and statistical developments.
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Klee GG. Assay configuration and analytic specificity may have major effects on prediction of clinical outcomes-- implications for reference standards. Clin Chem 2009; 55:848-9. [PMID: 19299538 DOI: 10.1373/clinchem.2009.124172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Sturgeon CM, Duffy MJ, Stenman UH, Lilja H, Brünner N, Chan DW, Babaian R, Bast RC, Dowell B, Esteva FJ, Haglund C, Harbeck N, Hayes DF, Holten-Andersen M, Klee GG, Lamerz R, Looijenga LH, Molina R, Nielsen HJ, Rittenhouse H, Semjonow A, Shih IM, Sibley P, Sölétormos G, Stephan C, Sokoll L, Hoffman BR, Diamandis EP. National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers. Clin Chem 2008; 54:e11-79. [DOI: 10.1373/clinchem.2008.105601] [Citation(s) in RCA: 458] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Background: Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.
Methods: Published reports relevant to use of tumor markers for 5 cancer sites—testicular, prostate, colorectal, breast, and ovarian—were critically reviewed.
Results: For testicular cancer, α-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. α-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is <10 μg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node–negative patients. CA15-3/BR27–29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer.
Conclusions: Implementation of these recommendations should encourage optimal use of tumor markers.
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Affiliation(s)
- Catharine M Sturgeon
- Department of Clinical Biochemistry, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Michael J Duffy
- Department of Pathology and Laboratory Medicine, St Vincent’s University Hospital and UCD School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Ulf-Håkan Stenman
- Department of Clinical Chemistry, Helsinki University Central Hospital, Helsinki, Finland
| | - Hans Lilja
- Departments of Clinical Laboratories, Urology, and Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Nils Brünner
- Section of Biomedicine, Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Denmark
| | - Daniel W Chan
- Departments of Pathology and Oncology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Richard Babaian
- Department of Urology, The University of Texas Anderson Cancer Center, Houston, TX
| | - Robert C Bast
- Department of Experimental Therapeutics, University of Texas Anderson Cancer Center, Houston, Texas, USA
| | | | - Francisco J Esteva
- Departments of Breast Medical Oncology, Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston TX
| | - Caj Haglund
- Department of Surgery, Helsinki University Central Hospital, Helsinki, Finland
| | - Nadia Harbeck
- Frauenklinik der Technischen Universität München, Klinikum rechts der Isar, Munich, Germany
| | - Daniel F Hayes
- Breast Oncology Program, University of Michigan Comprehensive Cancer Center, Ann Arbor, MI
| | - Mads Holten-Andersen
- Section of Biomedicine, Department of Veterinary Pathobiology, Faculty of Life Sciences, University of Copenhagen, Denmark
| | - George G Klee
- Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, MN
| | - Rolf Lamerz
- Department of Medicine, Klinikum of the University of Munich, Grosshadern, Germany
| | - Leendert H Looijenga
- Laboratory of Experimental Patho-Oncology, Erasmus MC-University Medical Center Rotterdam, and Daniel den Hoed Cancer Center, Rotterdam, the Netherlands
| | - Rafael Molina
- Laboratory of Biochemistry, Hospital Clinico Provincial, Barcelona, Spain
| | - Hans Jørgen Nielsen
- Department of Surgical Gastroenterology, Hvidovre Hospital, Copenhagen, Denmark
| | | | - Axel Semjonow
- Prostate Center, Department of Urology, University Clinic Muenster, Muenster, Germany
| | - Ie-Ming Shih
- Departments of Pathology and Oncology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Paul Sibley
- Siemens Medical Solutions Diagnostics, Glyn Rhonwy, Llanberis, Gwynedd, UK
| | | | - Carsten Stephan
- Department of Urology, Charité Hospital, Universitätsmedizin Berlin, Berlin, Germany
| | - Lori Sokoll
- Departments of Pathology and Oncology, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Barry R Hoffman
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
| | - Eleftherios P Diamandis
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
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He W, Kularatne SA, Kalli KR, Prendergast FG, Amato RJ, Klee GG, Hartmann LC, Low PS. Quantitation of circulating tumor cells in blood samples from ovarian and prostate cancer patients using tumor-specific fluorescent ligands. Int J Cancer 2008; 123:1968-73. [PMID: 18661519 DOI: 10.1002/ijc.23717] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Quantitation of circulating tumor cells (CTCs) can provide information on the stage of a malignancy, onset of disease progression and response to therapy. In an effort to more accurately quantitate CTCs, we have synthesized fluorescent conjugates of 2 high-affinity tumor-specific ligands (folate-AlexaFluor 488 and DUPA-FITC) that bind tumor cells >20-fold more efficiently than fluorescent antibodies. Here we determine whether these tumor-specific dyes can be exploited for quantitation of CTCs in peripheral blood samples from cancer patients. A CTC-enriched fraction was isolated from the peripheral blood of ovarian and prostate cancer patients by an optimized density gradient centrifugation protocol and labeled with the aforementioned fluorescent ligands. CTCs were then quantitated by flow cytometry. CTCs were detected in 18 of 20 ovarian cancer patients (mean 222 CTCs/ml; median 15 CTCs/ml; maximum 3,118 CTCs/ml), whereas CTC numbers in 16 gender-matched normal volunteers were negligible (mean 0.4 CTCs/ml; median 0.3 CTCs/ml; maximum 1.5 CTCs/ml; p < 0.001, chi(2)). CTCs were also detected in 10 of 13 prostate cancer patients (mean 26 CTCs/ml, median 14 CTCs/ml, maximum 94 CTCs/ml) but not in 18 gender-matched healthy donors (mean 0.8 CTCs/ml, median 1, maximum 3 CTC/ml; p < 0.0026, chi(2)). Tumor-specific fluorescent antibodies were much less efficient in quantitating CTCs because of their lower CTC labeling efficiency. Use of tumor-specific fluorescent ligands to label CTCs in peripheral blood can provide a simple, accurate and sensitive method for determining the number of cancer cells circulating in the bloodstream.
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Affiliation(s)
- Wei He
- Department of Chemistry, Purdue University, West Lafayette, IN 47906, USA
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