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Kaufmann B, Pellegrino P, Zuluaga L, Ben-David R, Müntener M, Keller EX, Spanaus K, von Eckardstein A, Gorin MA, Poyet C. Interassay Variability and Clinical Implications of Five Different Prostate-specific Antigen Assays. EUR UROL SUPPL 2024; 63:4-12. [PMID: 38558765 PMCID: PMC10981008 DOI: 10.1016/j.euros.2024.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2024] [Indexed: 04/04/2024] Open
Abstract
Background and objective Prostate-specific antigen (PSA) remains a critical marker for prostate cancer (PCa) detection and monitoring. Recognising historical variability in PSA assays and the evolution of assay technology and calibration, this study aims to reassess interassay variability using the latest generation of five assays in a contemporary cohort of men undergoing prostate biopsy. Methods Five different commercially available PSA assays were tested in a blood sample of 76 men before undergoing a prostate biopsy. Total PSA (tPSA) and free-to-total PSA ratio (%fPSA) were compared across assays, using Roche (Basel, Switzerland) as the benchmark, and correlated with biopsy outcome to analyse the impact on PCa diagnosis. The statistical analysis included Passing-Bablok regression and Bland-Altman plots, with a p value threshold of <0.05 for significance. Key findings and limitations Among the 76 men, 28 (36.8%) were diagnosed with significant PCa (defined as International Society of Urological Pathology grade ≥2). A high correlation was observed between tPSA and %fPSA values among the different PSA assays tested (r2 ≥ 0.9). The Passing-Bablok analysis showed that tPSA results varied substantially among the assays, with slopes ranging between 0.78 and 1.04. Compared with the tPSA of Roche, tPSA values were on average 20.7% lower by Beckman (Oststeinbeck, Germany), 15.2% lower by Abbott (Chicago, IL, USA), 6.1% lower by Diasorin (Saluggia, Italy), and 9.6% higher by Brahms (Hennigsdorf, Germany; p < 0.001 for all). The %fPSA values by Abbott and Brahms were higher at 15.7% and 10.6%, respectively (p < 0.001), while the Beckman and Diasorin values had minimal differences of -0.3% and 2.3%, respectively (p > 0.05). The variability across assays would have resulted in discrepancies in both the sensitivity and the specificity for tPSA and %fPSA by at least 14%, depending on the cut-offs applied. Conclusions and clinical implications Despite the use of the latest PSA assays, relevant variability of tPSA and %fPSA results can be observed among different assays. There is an urgent need for standardised calibration methods and greater awareness among practitioners concerning interassay variability. Clinicians should acknowledge that clinically relevant thresholds may depend on the specific PSA assay and that ideally the same assay is applied over time for better clinical decision-making. Patient summary Prostate-specific antigen (PSA) is a critical marker for prostate cancer (PCa) detection and monitoring. However, significant variations were observed in the results of the latest PSA assays. Thus, standardised calibration methods and greater awareness among practitioners concerning interassay variability are needed.
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Affiliation(s)
- Basil Kaufmann
- Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Paloma Pellegrino
- Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Laura Zuluaga
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Reuben Ben-David
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michael Müntener
- Department of Urology, Municipal Hospital of Zurich, Zurich, Switzerland
| | - Etienne X. Keller
- Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Katharina Spanaus
- Institute for Clinical Chemistry, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
| | - Arnold von Eckardstein
- Institute for Clinical Chemistry, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
| | - Michael A. Gorin
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Cédric Poyet
- Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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von Eyben FE, Kairemo K, Kapp DS. Prostate-Specific Antigen as an Ultrasensitive Biomarker for Patients with Early Recurrent Prostate Cancer: How Low Shall We Go? A Systematic Review. Biomedicines 2024; 12:822. [PMID: 38672176 PMCID: PMC11048591 DOI: 10.3390/biomedicines12040822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/25/2023] [Accepted: 03/05/2024] [Indexed: 04/28/2024] Open
Abstract
Serum prostate-specific antigen (PSA) needs to be monitored with ultrasensitive PSA assays (uPSAs) for oncologists to be able to start salvage radiotherapy (SRT) while PSA is <0.5 µg/L for patients with prostate cancer (PCa) relapsing after a radical prostatectomy (RP). Our systematic review (SR) aimed to summarize uPSAs for patients with localized PCa. The SR was registered as InPLASY2023110084. We searched for studies on Google Scholar, PUBMED and reference lists of reviews and studies. We only included studies on uPSAs published in English and excluded studies of women, animals, sarcoidosis and reviews. Of the 115 included studies, 39 reported PSA assay methods and 76 reported clinical findings. Of 67,479 patients, 14,965 developed PSA recurrence (PSAR) and 2663 died. Extremely low PSA nadir and early developments of PSA separated PSAR-prone from non-PSAR-prone patients (cumulative p value 3.7 × 1012). RP patients with the lowest post-surgery PSA nadir and patients who had the lowest PSA at SRT had the fewest deaths. In conclusion, PSA for patients with localized PCa in the pre-PSAR phase of PCa is strongly associated with later PSAR and survival. A rising but still exceedingly low PSA at SRT predicts a good 5-year overall survival.
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Affiliation(s)
| | - Kalevi Kairemo
- Department of Molecular Radiotherapy & Nuclear Medicine, Docrates Cancer Center, FI-00185 Helsinki, Finland;
| | - Daniel S. Kapp
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Lundgren PO, Kjellman A, Norming U, Gustafsson O. Reply to the letter by Ferraro and Biganzoli. BJU Int 2022; 129:419. [PMID: 35297161 DOI: 10.1111/bju.15642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Per-Olof Lundgren
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Anders Kjellman
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Ulf Norming
- Department of Clinical Science and Education, Karolinska Institutet and Södersjukhuset, Stockholm, Sweden
| | - Ove Gustafsson
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
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4
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Jalali A, Foley RW, Maweni RM, Murphy K, Lundon DJ, Lynch T, Power R, O'Brien F, O'Malley KJ, Galvin DJ, Durkan GC, Murphy TB, Watson RW. A risk calculator to inform the need for a prostate biopsy: a rapid access clinic cohort. BMC Med Inform Decis Mak 2020; 20:148. [PMID: 32620120 PMCID: PMC7333322 DOI: 10.1186/s12911-020-01174-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 06/29/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prostate cancer (PCa) represents a significant healthcare problem. The critical clinical question is the need for a biopsy. Accurate risk stratification of patients before a biopsy can allow for individualised risk stratification thus improving clinical decision making. This study aims to build a risk calculator to inform the need for a prostate biopsy. METHODS Using the clinical information of 4801 patients an Irish Prostate Cancer Risk Calculator (IPRC) for diagnosis of PCa and high grade (Gleason ≥7) was created using a binary regression model including age, digital rectal examination, family history of PCa, negative prior biopsy and Prostate-specific antigen (PSA) level as risk factors. The discrimination ability of the risk calculator is internally validated using cross validation to reduce overfitting, and its performance compared with PSA and the American risk calculator (PCPT), Prostate Biopsy Collaborative Group (PBCG) and European risk calculator (ERSPC) using various performance outcome summaries. In a subgroup of 2970 patients, prostate volume was included. Separate risk calculators including the prostate volume (IPRCv) for the diagnosis of PCa (and high-grade PCa) was created. RESULTS IPRC area under the curve (AUC) for the prediction of PCa and high-grade PCa was 0.6741 (95% CI, 0.6591 to 0.6890) and 0.7214 (95% CI, 0.7018 to 0.7409) respectively. This significantly outperforms the predictive ability of cancer detection for PSA (0.5948), PCPT (0.6304), PBCG (0.6528) and ERSPC (0.6502) risk calculators; and also, for detecting high-grade cancer for PSA (0.6623) and PCPT (0.6804) but there was no significant improvement for PBCG (0.7185) and ERSPC (0.7140). The inclusion of prostate volume into the risk calculator significantly improved the AUC for cancer detection (AUC = 0.7298; 95% CI, 0.7119 to 0.7478), but not for high-grade cancer (AUC = 0.7256; 95% CI, 0.7017 to 0.7495). The risk calculator also demonstrated an increased net benefit on decision curve analysis. CONCLUSION The risk calculator developed has advantages over prior risk stratification of prostate cancer patients before the biopsy. It will reduce the number of men requiring a biopsy and their exposure to its side effects. The interactive tools developed are beneficial to translate the risk calculator into practice and allows for clarity in the clinical recommendations.
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Affiliation(s)
- Amirhossein Jalali
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland. .,UCD School of Medicine, University College Dublin, Dublin, Ireland.
| | - Robert W Foley
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.,UCD School of Medicine, University College Dublin, Dublin, Ireland
| | - Robert M Maweni
- UCD School of Medicine, University College Dublin, Dublin, Ireland
| | - Keefe Murphy
- UCD School of Mathematics and Statistics, University College Dublin, Dublin, Ireland.,Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland
| | - Dara J Lundon
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.,UCD School of Medicine, University College Dublin, Dublin, Ireland
| | - Thomas Lynch
- Department of Urology, St. James University Hospital, Dublin, Ireland
| | - Richard Power
- Department of Urology, Beaumont Hospital, Dublin, Ireland
| | - Frank O'Brien
- Department of Urology, University Hospital Waterford, Waterford, Ireland.,Department of Urology, Cork University Hospital, Cork, Ireland
| | - Kieran J O'Malley
- Department of Urology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - David J Galvin
- Department of Urology, Mater Misericordiae University Hospital, Dublin, Ireland.,Department of Urology, St Vincent's University Hospital, Dublin, Ireland
| | - Garrett C Durkan
- Department of Urology, University Hospital Galway, Galway, Ireland.,Department of Urology, University Hospital Limerick, Limerick, Ireland
| | - T Brendan Murphy
- UCD School of Mathematics and Statistics, University College Dublin, Dublin, Ireland.,Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland
| | - R William Watson
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.,UCD School of Medicine, University College Dublin, Dublin, Ireland
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5
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Ferguson J, Patel D, Atkinson E, Rigsby P, Burns C. Continued provision of WHO International Standards for total and free PSA: Content and commutability of replacement preparations. Clin Biochem 2019; 71:58-66. [DOI: 10.1016/j.clinbiochem.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 07/03/2019] [Accepted: 07/06/2019] [Indexed: 10/26/2022]
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6
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Okullo A, Penkoff P, Patel MI. Laboratory methods cause ultrasensitive prostate-specific antigen fluctuations. ANZ J Surg 2017; 87:651-652. [PMID: 28876540 DOI: 10.1111/ans.14043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 03/21/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Alfin Okullo
- Department of Surgery, Westmead Hospital, Sydney, New South Wales, Australia.,Discipline in Surgery, University of Sydney, Sydney, New South Wales, Australia
| | - Peter Penkoff
- Department of Surgery, Westmead Hospital, Sydney, New South Wales, Australia
| | - Manish I Patel
- Department of Surgery, Westmead Hospital, Sydney, New South Wales, Australia.,Discipline in Surgery, University of Sydney, Sydney, New South Wales, Australia
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Lee GR, Fitzgibbon MC, O'Shea P. Laboratory services: regaining and maintaining control. Int J Health Care Qual Assur 2017; 29:507-22. [PMID: 27256774 DOI: 10.1108/ijhcqa-08-2015-0098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Purpose - After implementing an internal quality control (IQC) programme, the purpose of this paper is to maintain the requisite analytical performance for clinical laboratory staff, thereby safeguarding patient test results for their intended medical purpose. Design/methodology/approach - The authors address how quality can be maintained and if lost, how it can be regained. The methodology is based on the experience working in clinical laboratory diagnostics and is in accord with both international accreditation requirements and laboratory best practice guidelines. Findings - Monitoring test performance usually involves both prospective and retrospective IQC data analysis. The authors present a number of different approaches together with software tools currently available and emerging, that permit performance monitoring at the level of the individual analyser, across analysers and laboratories (networks). The authors make recommendations on the appropriate response to IQC rule warnings, failures and metrics that indicate analytical control loss, that either precludes further analysis, or signifies deteriorating performance and eventual unsuitability. The authors provide guidance on systematic troubleshooting, to identify undesirable performance and consider risk assessment preventive measures and continuous quality improvement initiatives; e.g., material acceptance procedures, as tools to help regain and maintain analytical control and minimise potential for patient harm. Practical implications - The authors provide a template for use by laboratory scientific personnel that ensures the optimal monitoring of analytical test performance and response when it changes undesirably. Originality/value - The proposed template has been designed to meet the International Organisation for Standardisation for medical laboratories ISO15189:2012 requirements and therefore includes the use of External Quality Assessment and patient results data, as an adjunct to IQC data.
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Affiliation(s)
- Graham R Lee
- Department of Clinical Biochemistry and Diagnostic Endocrinology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Maria C Fitzgibbon
- Department of Clinical Biochemistry and Diagnostic Endocrinology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Paula O'Shea
- Department of Clinical Biochemistry, Saolta Hospital Group, Galway, Ireland
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8
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Harrison S, Tilling K, Turner EL, Lane JA, Simpkin A, Davis M, Donovan J, Hamdy FC, Neal DE, Martin RM. Investigating the prostate specific antigen, body mass index and age relationship: is an age-BMI-adjusted PSA model clinically useful? Cancer Causes Control 2016; 27:1465-1474. [PMID: 27830401 PMCID: PMC5108825 DOI: 10.1007/s10552-016-0827-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 10/26/2016] [Indexed: 12/14/2022]
Abstract
PURPOSE Previous studies indicate a possible inverse relationship between prostate-specific antigen (PSA) and body mass index (BMI), and a positive relationship between PSA and age. We investigated the associations between age, BMI, PSA, and screen-detected prostate cancer to determine whether an age-BMI-adjusted PSA model would be clinically useful for detecting prostate cancer. METHODS Cross-sectional analysis nested within the UK ProtecT trial of treatments for localized cancer. Of 18,238 men aged 50-69 years, 9,457 men without screen-detected prostate cancer (controls) and 1,836 men with prostate cancer (cases) met inclusion criteria: no history of prostate cancer or diabetes; PSA < 10 ng/ml; BMI between 15 and 50 kg/m2. Multivariable linear regression models were used to investigate the relationship between log-PSA, age, and BMI in all men, controlling for prostate cancer status. RESULTS In the 11,293 included men, the median PSA was 1.2 ng/ml (IQR: 0.7-2.6); mean age 61.7 years (SD 4.9); and mean BMI 26.8 kg/m2 (SD 3.7). There were a 5.1% decrease in PSA per 5 kg/m2 increase in BMI (95% CI 3.4-6.8) and a 13.6% increase in PSA per 5-year increase in age (95% CI 12.0-15.1). Interaction tests showed no evidence for different associations between age, BMI, and PSA in men above and below 3.0 ng/ml (all p for interaction >0.2). The age-BMI-adjusted PSA model performed as well as an age-adjusted model based on National Institute for Health and Care Excellence (NICE) guidelines at detecting prostate cancer. CONCLUSIONS Age and BMI were associated with small changes in PSA. An age-BMI-adjusted PSA model is no more clinically useful for detecting prostate cancer than current NICE guidelines. Future studies looking at the effect of different variables on PSA, independent of their effect on prostate cancer, may improve the discrimination of PSA for prostate cancer.
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Affiliation(s)
- Sean Harrison
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK.
| | - Kate Tilling
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Emma L Turner
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - J Athene Lane
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Andrew Simpkin
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Michael Davis
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Jenny Donovan
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
| | - Freddie C Hamdy
- Nuffield Department of Surgery, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - David E Neal
- University Department of Oncology, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Richard M Martin
- School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK
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McJimpsey EL. Molecular Form Differences Between Prostate-Specific Antigen (PSA) Standards Create Quantitative Discordances in PSA ELISA Measurements. Sci Rep 2016; 6:22050. [PMID: 26911983 PMCID: PMC4766849 DOI: 10.1038/srep22050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/04/2016] [Indexed: 11/09/2022] Open
Abstract
The prostate-specific antigen (PSA) assays currently employed for the detection of prostate cancer (PCa) lack the specificity needed to differentiate PCa from benign prostatic hyperplasia and have high false positive rates. The PSA calibrants used to create calibration curves in these assays are typically purified from seminal plasma and contain many molecular forms (intact PSA and cleaved subforms). The purpose of this study was to determine if the composition of the PSA molecular forms found in these PSA standards contribute to the lack of PSA test reliability. To this end, seminal plasma purified PSA standards from different commercial sources were investigated by western blot (WB) and in multiple research grade PSA ELISAs. The WB results revealed that all of the PSA standards contained different mass concentrations of intact and cleaved molecular forms. Increased mass concentrations of intact PSA yielded higher immunoassay absorbance values, even between lots from the same manufacturer. Standardization of seminal plasma derived PSA calibrant molecular form mass concentrations and purification methods will assist in closing the gaps in PCa testing measurements that require the use of PSA values, such as the % free PSA and Prostate Health Index by increasing the accuracy of the calibration curves.
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Affiliation(s)
- Erica L McJimpsey
- National Institute of Standards and Technology, Material Measurement Laboratory, Gaithersburg, Maryland, 20878, USA.,Department of Chemistry, Western Illinois University, Macomb, Illinois, 61455, USA
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10
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Alcover J, Filella X. Identification of Candidates for Active Surveillance: Should We Change the Current Paradigm? Clin Genitourin Cancer 2015; 13:499-504. [DOI: 10.1016/j.clgc.2015.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 06/05/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
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11
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Predicting prostate cancer: analysing the clinical efficacy of prostate cancer risk calculators in a referral population. Ir J Med Sci 2015; 184:701-6. [DOI: 10.1007/s11845-015-1291-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 03/29/2015] [Indexed: 10/23/2022]
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12
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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] [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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13
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Foj L, Filella X, Alcover J, Augé JM, Escudero JM, Molina R. Variability of assay methods for total and free PSA after WHO standardization. Tumour Biol 2013; 35:1867-73. [PMID: 24092573 DOI: 10.1007/s13277-013-1249-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 09/23/2013] [Indexed: 01/10/2023] Open
Abstract
The variability of total PSA (tPSA) and free PSA (fPSA) results among commercial assays has been suggested to be decreased by calibration to World Health Organization (WHO) reference materials. To characterize the current situation, it is necessary to know its impact in the critical cutoffs used in clinical practice. In the present study, we tested 167 samples with tPSA concentrations of 0 to 20 μg/L using seven PSA and six fPSA commercial assays, including Access, ARCHITECT i2000, ADVIA Centaur XP, IMMULITE 2000, Elecsys, and Lumipulse G1200, in which we only measured tPSA. tPSA and fPSA were measured in Access using the Hybritech and WHO calibrators. Passing-Bablok analysis was performed for PSA, and percentage of fPSA with the Hybritech-calibrated access comparison assay. For tPSA, relative differences were more than 10 % at 0.2 μg/L for ARCHITECT i2000, and at a critical concentration of 3, 4, and 10 μg/L, the relative difference was exceeded by ADVIA Centaur XP and WHO-calibrated Access. For percent fPSA, at a critical concentration of 10 %, the 10 % relative difference limit was exceeded by IMMULITE 2000 assay. At a critical concentration of 20 and 25 %, ADVIA Centaur XP, ARCHITECT i2000, and IMMULITE 2000 assays exceeded the 10 % relative difference limit. We have shown significant discordances between assays included in this study despite advances in standardization conducted in the last years. Further harmonization efforts are required in order to obtain a complete clinical concordance.
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Affiliation(s)
- L Foj
- Department of Biochemistry and Molecular Genetics (CDB), Hospital Clínic, IDIBAPS, C/ Villarroel, 170, 08036, Barcelona, Catalonia, Spain
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14
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Forde JC, Daly PJ, White S, Morrin M, Smyth GP, O’Neill BDP, Power RE. A single centre experience of active surveillance as management strategy for low-risk prostate cancer in Ireland. Ir J Med Sci 2013; 183:377-82. [DOI: 10.1007/s11845-013-1024-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/19/2013] [Indexed: 11/29/2022]
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15
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The number of tPSA tests continues to rise and variation in testing practices persists: a survey of laboratory services in Ireland 2008-2010. Ir J Med Sci 2013; 183:369-75. [PMID: 24072433 DOI: 10.1007/s11845-013-1022-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 09/17/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Ireland had the highest incidence of prostate cancer in Europe in 2008, due to widespread prostate specific antigen (PSA) testing. AIMS To investigate practices and costs of PSA testing in Ireland, 2008-2010. METHODS Postal laboratory questionnaire. Results were compared with 2006 and 2007 surveys. RESULTS Response rate was 95 % (42/44). In 2010, 37 laboratories measured total PSA (tPSA); 10 measured free PSA (fPSA). Eight assays were used and cut-offs to define 'normal' tPSA varied widely. There was a 9.9 % annual increase in the number of tPSA tests and a -31 % annual decrease in the number of fPSA, 2006-2010. A 100-fold difference in tPSA workload was observed across laboratories. In 2010, the estimated cost of PSA testing was <euro>3,649,984 (95 % CI <euro>2,532,745-<euro>4,767,222). CONCLUSIONS Health service costs of PSA testing are significant. The number of tPSA tests continues to rise; fPSA use fell by almost one-third. Inter-laboratory variation in testing practices persists. These have potentially important clinical consequences for men and need to be addressed.
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