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Boegemann M, Arsov C, Hadaschik B, Herkommer K, Imkamp F, Nofer JR, Gerß J, Albers P, Semjonow A. Discordant prostate specific antigen test results despite WHO assay standardization. Int J Biol Markers 2018; 33:275-282. [DOI: 10.1177/1724600818754750] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Introduction: Total PSA (tPSA) and free PSA (fPSA) are the most commonly used biomarkers for early detection of prostate cancer. Despite standardization efforts, many available PSA assays may still produce discordant results. In the present study, we compared four PSA assays calibrated to the WHO standards 96/670 and 96/668 for tPSA and fPSA, respectively. Methods: Within the scope of the Prostate Cancer Early Detection Study Based on a ‘‘Baseline’’ PSA Value in Young Men (PROBASE), we tested tPSA and fPSA in serum samples from 50 patients in the four different PROBASE sites using four WHO-calibrated assays from Roche (Elecsys, Cobas), Beckman-Coulter (Access-II) and Siemens (ADVIA Centaur). The comparison was performed using the Passing–Bablok regression method. Results: Compared to Access, the median tPSA levels for Centaur, Elecsys, and Cobas were +3%, +11%–20%, and +17%–23%, respectively, while for median fPSA levels the differences for Centaur, Elecsys, and Cobas were +49%, +29%–31%, and +22%, respectively. Discussion: Despite all investigated assays being WHO-calibrated, the Elecsys and Cobas tPSA assays produced considerably higher results than the Access and Centaur assays. Differences in fPSA-recovery between all investigated assays were even more pronounced. When applying the tPSA cutoff of 3.1 μg/L recommended for WHO-calibrated assays, the use of higher calibrated assays may lead to unnecessary prostate biopsies. Conversely, if the historical threshold of 4 μg/L is applied when using WHO-calibrated assays, it could lead to falsely omitted prostate biopsies.
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Affiliation(s)
- Martin Boegemann
- Department of Urology, Prostate Center, University Hospital Münster, Muenster, Germany
| | - Christian Arsov
- Department of Urology, Dusseldorf University Medical Center, Dusseldorf, Germany
| | - Boris Hadaschik
- Department of Urology, University Hospital Essen, Essen, Germany
| | - Kathleen Herkommer
- Department of Urology, Technical University of Munich Klinikum rechts der Isar, Munich, Germany
| | - Florian Imkamp
- Department of Urology, Hannover University Medical Center, Hannover, Germany
| | - Jerzy-Roch Nofer
- Center for Laboratory Medicine, University Hospital Muenster, Muenster, Germany
| | - Joachim Gerß
- Institute of Biostatistics and Clinical Research of the Westfalian Wilhelms-University Muenster, Muenster, Germany
| | - Peter Albers
- Department of Urology, Dusseldorf University Medical Center, Dusseldorf, Germany
| | - Axel Semjonow
- Department of Urology, Prostate Center, University Hospital Münster, Muenster, Germany
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Vignati G, Giovanelli L. Standardization of PSA Measures: A Reappraisal and an Experience with WHO Calibration of Beckman Coulter Access Hybritech Total and Free PSA. Int J Biol Markers 2018; 22:295-301. [DOI: 10.1177/172460080702200409] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Prostate-specific antigen (PSA) is the serum biomarker most widely used in prostate diseases. Since there is significant variation in PSA results among non-equimolar assays, the 90:10 ratio of complexed PSA to free PSA (the Stanford standard) was proposed as standardization; this became the basis for the PSA mass standards WHO 96/670 for tPSA and 96/668 for fPSA. Nevertheless, recent publications underlined the lack of interchangeability between different commercial assays, all claimed to be equimolar and calibrated to the WHO standard. Importantly, the WHO calibration yields about 16–20% lower PSA results. Manufacturers that have chosen to calibrate existing assays to the mass value of WHO 96/760 have introduced a significant negative bias compared to the Hybritech assay calibration; this bias is transferred to clinical evaluation if the cutoff of 4 ng/mL, clinically validated for the Hybritech assay, is maintained with the WHO calibration. Beckman Coulter recently provided the option of calibrating the Access Hybritech PSA and free PSA assays to the WHO standard introducing a different clinical cutoff. Using two different reagent lots, we tested about 200 routine patients for tPSA and fPSA with both calibrations; we also calculated the f/tPSA ratio with both calibrated methods. Moreover, we verified the analytical sensitivity and inter- and intra-assay variability. In accordance with the claim of the manufacturer, the results obtained with the WHO calibration showed a negative bias of about 25% and, as expected, no significant difference was found for % f/tPSA. The same bias was found when retesting samples of the External Quality Assessment Scheme of the Institute of Clinical Physiology of the National Research Council in Pisa. Based on this experience we decided for the moment to keep the Hybritech calibration, in order to avoid cutoff changes during patient follow-up. Moreover, we have started to provide information to clinicians aimed at the alignment of our results with the WHO standardization.
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Affiliation(s)
- G. Vignati
- Center of Endocrine and Metabolic Diseases, G. Fornaroli Hospital, Magenta (Milan) - Italy
| | - L. Giovanelli
- Center of Endocrine and Metabolic Diseases, G. Fornaroli Hospital, Magenta (Milan) - Italy
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Forde JC, Marignol L, Blake O, McDermott T, Grainger R, Crowley VE, Lynch TH. Standardization of assay methods reduces variability of total PSA measurements: an Irish study. BJU Int 2012; 110:644-50. [DOI: 10.1111/j.1464-410x.2011.10923.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Stephan C, Klaas M, Müller C, Schnorr D, Loening SA, Jung K. Interchangeability of measurements of total and free prostate-specific antigen in serum with 5 frequently used assay combinations: an update. Clin Chem 2006; 52:59-64. [PMID: 16391327 DOI: 10.1373/clinchem.2005.059170] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The comparability of total and free prostate-specific antigen (tPSA and fPSA) results among commercial PSA assays has been suggested to be improved by calibration to WHO PSA reference materials and the development of equimolar-response assays. To characterize the current situation, we assessed 5 frequently used commercial assay combinations for tPSA and fPSA regarding the interchangeability of the PSA values and the ratio of fPSA to tPSA (%fPSA), equimolar characteristics, and diagnostic accuracy. METHODS Sera from 314 patients with prostate cancer (PCa) and 282 men with no evidence of prostate cancer (NPCa) were measured with tPSA and fPSA assays from Abbott (AxSYM), Beckman Coulter (Access), Diagnostic Products Corporation (Immulite 2000), and Roche (Elecsys 2010) and with tPSA and complexed PSA (cPSA) assays from Bayer (ADVIA Centaur). RESULTS Method comparisons (Passing and Bablok regressions; Bland-Altman plots) showed assay-dependent results for tPSA, fPSA, and %fPSA. With the Access tPSA values taken as 100%, tPSA concentrations varied from 87% (AxSYM and ADVIA Centaur) to 115% (Immulite), leading to different numbers of patients classified according to the commonly recommended tPSA cutoffs for performing a biopsy. Different %fPSA values also led to assay-dependent ROC analysis results, a finding that shows the importance for the diagnostic accuracy. CONCLUSION Interchangeability of tPSA, fPSA, and %fPSA values obtained by commercial PSA assays remains inadequate, but attention to this issue may minimize the misinterpretation of PSA results obtained by different assays.
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Affiliation(s)
- Carsten Stephan
- Department of Urology, University Hospital Charité, Berlin, Germany
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Hara N, Okuizumi M, Koike H, Kawaguchi M, Bilim V. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a useful modality for the precise detection and staging of early prostate cancer. Prostate 2005; 62:140-7. [PMID: 15389803 DOI: 10.1002/pros.20124] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND The aim of this study was to visualize early stage prostate cancer (Cap) in a clinical setting. In previous studies, the results of magnetic resonance imaging (MRI) for screening Cap have rarely been confirmed by well-designed multisite prostate biopsy. METHODS The prostate glands of 90 men with elevated prostate-specific antigen (PSA) were imaged by dynamic contrast-enhanced MRI (DCE-MRI) before transrectal ultrasound-guided 14-cores prostate biopsy. Each core was divided into three subcore fractions (total of 42 fractions) to generate a histological localization diagram, which was compared with localization-visualized DCE-MRI. RESULTS The detection rate of Cap in 57 patients with PSA < 10.0 ng/ml was 36.8% as determined by the initial biopsy. DCE-MRI uncovered 92.9% of the clinically significant Caps and its specificity was 96.2% for the first biopsy session. One case with positive DCE-MRI and a negative primary biopsy was positive with additional biopsies. All of 26 DCE-MRI positive cases had significant Cap, and two of eight patients with histological Cap and negative or equivocal imaging had significant cancer. In total, 9 of 20 cases with DCE-MRI stage T2 underwent radical prostatectomy. All of them had organ-confined disease, although 33-77% (mean 63%) of them were expected to be rated T3 or higher by Partin's table. CONCLUSIONS DCE-MRI can identify early stage Cap with high sensitivity and specificity, and can predict the histological grade to some extent. DCE-MRI prior to biopsy should be applied to younger patients with surgical indications. Otherwise, we recommend the definitive diagnosis of Cap by utilizing DCE-MRI alone.
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Affiliation(s)
- Noboru Hara
- Department of Urology, Labor Welfare Niigata Rousai Hospital, Joetsu, Japan.
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Hara N, Koike H, Ogino S, Okuizumi M, Kawaguchi M. Application of serum PSA to identify acute bacterial prostatitis in patients with fever of unknown origin or symptoms of acute pyelonephritis. Prostate 2004; 60:282-8. [PMID: 15264238 DOI: 10.1002/pros.20077] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Exclusion of prostatitis in screening for prostate cancer (Cap) is a matter of concern in the prostate-specific antigen (PSA) era. Yet, the identification of acute bacterial prostatitis (ABP), intentionally utilizing PSA in patients with pyrexia has been scarcely reported. METHODS In total, 39 men, who presented at our department with a fever higher than 38.3 degrees C, were randomly selected. We investigated the fraction of patients who had serum PSA levels higher than 4.0 ng/ml and categorized them according to an initial diagnosis of pyelonephritis, ABP, other urogenital infections, and fever of unknown origin (FUO). RESULTS Six of nine cases initially diagnosed as pyelonephritis, presented with elevated PSA levels between 9.5 and 75.1 ng/ml. All six cases of clinically diagnosed prostatitis had PSA elevated between 4.1 and 13.6 ng/ml. In 8 of 18 FUO cases, PSA was elevated between 5.1 and 77.0 ng/ml. PSA levels significantly correlated with age (P < 0.005). All 20 patients with elevated PSA received antibiotics, and serum PSA was significantly reduced in all cases (P < 0.001) together with the alleviation of fever and normalization of CRP. CONCLUSIONS PSA is a prompt and steady diagnostic tool for identifying ABP that might be missed or misdiagnosed. We recommend the measurement of PSA in cases not only with urologic infection but also puzzling pyrexia.
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Affiliation(s)
- Noboru Hara
- Department of Urology, Labor Welfare Niigata Rousai Hospital, Touncho, Japan.
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Roobol MJ, Schröder FH. European Randomized Study of Screening for Prostate Cancer: achievements and presentation. BJU Int 2004; 92 Suppl 2:117-22. [PMID: 14983969 DOI: 10.1111/j.1464-410x.2003.4698x.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Four elements are crucial to successful pharmacokinetic-pharmacodynamic (PK/PD) modelling and simulation for efficient and effective rational drug development: (i) mechanism-based biomarker selection and correlation to clinical endpoints; (ii) quantification of drug and/or metabolites in biological fluids under good laboratory practices (GLP); (iii) GLP-like biomarker method validation and measurements and; (iv) mechanism-based PK/PD modelling and validation. Biomarkers can provide great predictive value in early drug development if they reflect the mechanism of action for the intervention even if they do not become surrogate endpoints. PK/PD modelling and simulation can play a critical role in this process. Data from genomic and proteomics differentiating healthy versus disease states lead to biomarker discovery and identification. Multiple genes control complex diseases via hosts of gene products in biometabolic pathways and cell/organ signal transduction. Pilot exploratory studies should be conducted to identify pivotal biomarkers to be used for predictive clinical assessment of disease progression and the effect of drug intervention. Most biomarkers are endogenous macromolecules, which could be measured in biological fluids. Many exist in heterogeneous forms with varying activity and immunoreactivity, posting challenges for bioanalysis. Reliable and selective assays could be validated under a GLP-like environment for quantitative methods. While the need for consistent reference standards and quality control monitoring during sample analysis for biomarker assays are similar to that of drug molecules, many biomarkers have special requirements for sample collection that demand a well coordinated team management. Bioanalytical methods should be validated to meet study objectives at various drug development stages, and possess adequate performance to quantify biochemical responses specific to the target disease progression and drug intervention. Protocol design to produce sufficient data for PK/PD modelling would be more complex than that of PK. Knowledge of mechanism from discovery and preclinical studies are helpful for planning clinical study designs in cascade, sequential, crossover or replicate mode. The appropriate combination of biomarker identification and selection, bioanalytical methods development and validation for drugs and biomarkers, and mechanism-based PK/PD models for fitting data and predicting future clinical endpoints/outcomes provide powerful insights and guidance for effective and efficient rational drug development, toward safe and efficacious medicine for individual patients.
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Colburn WA. Biomarkers in drug discovery and development: from target identification through drug marketing. J Clin Pharmacol 2003; 43:329-41. [PMID: 12723454 DOI: 10.1177/0091270003252480] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Biomarkers of disease play an important role in medicine and have begun to assume a greater role in drug discovery and development. The challenge for biomarkers is to allow earlier, more robust drug safety and efficacy measurements. Their role in drug development will continue to grow for the foreseeable future. For biomarkers to assume their rightful role, greater understanding of the mechanism of disease progression and therapeutic intervention is needed. In addition, greater understanding of the requirements for biomarker selection and validation, biomarker assay method validation and application, and clinical endpoint validation and application is needed. Biomarkers need to be taken into account while the therapeutic target is still being identified and the concept is being formulated. Biomarkers need to be incorporated into a continuous cycle that takes what is learned from the discovery and development of one series of biomarkers and translates it into the next series of biomarkers. Optimum biomarker development and application will require a team approach because of the multifaceted nature of biomarker selection, validation, and application, using such techniques as pharmacoepidemiology, pharmacogenetics, pharmacogenomics, and functional proteomics; bioanalytical method development and validation; disease process and therapeutic intervention assessments; and pharmacokinetic/pharmacodynamic modeling and simulation to improve and refine drug development. The potential for biomarkers in medicine and drug development will be limited by the least effective component of the processes. The team approach will minimize the potential for the least effective component to be fatal to the rest of the process. As scientific/regulatory foundations for biomarkers in medicine and drug development begin to be established, successes and applications will need to be effectively communicated with all of the stakeholders, including not only internal and external drug developers and regulators but also the medical community, to ensure that biomarkers are totally integrated into drug discovery and development as well as the practice of medicine.
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Oberpenning F, Weining C, Brandt B, De Angelis G, Heinecke A, Hamm M, Stieber P, Hertle L, Schmid HP, Semjonow A. A new modification of the Chiron ACS assay for total prostate-specific antigen achieves equimolar response characteristics and improves the detection of prostate cancer. Clin Chem Lab Med 2003; 41:90-4. [PMID: 12636056 DOI: 10.1515/cclm.2003.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Nonequimolar-response assays for prostate-specific antigen (PSA) are criticized for overestimating total PSA in some men without prostate cancer (PCA), and underestimating total PSA in some men with PCA. We recently studied three nonequimolar-response PSA assays that had undergone modifications. While two of the studied assays achieved equimolar-response characteristics with improved areas under receiver operating characteristic (ROC) curves (AUC), the modification of the Chiron ACS PSA assay (ACS PSA2, Chiron) failed to achieve this. Recently, the ACS assay underwent another modification (ACS PSA, Bayer), which we investigated. Sera from 305 men (155 without and 150 with PCA, PSA > or = 2 and < or = 30 microg/l, Tandem-E) were measured using both modifications of the ACS assay and equimolar-response reference methods (Tandem-R free and Tandem-E, Hybritech). Molar response relative to the reference method and clinical performance (comparison of AUCs) between the previous and new ACS assay modifications were studied. The new modification of the ACS assay (ACS PSA, Bayer) achieved equimolar-response characteristics but reported lower values (average 10%) than the Tandem-E assay. Compared to the previous modification (ACS PSA2, Chiron), a 3% improvement in AUC (p = 0.01) was found. Using results of the redesigned equimolar-response assay (ACS PSA, Bayer), we calculated that 6 of 155 men without PCA in this sample set could be spared unnecessary biopsy compared with the previous nonequimolar-response assay (ACS PSA2, Chiron) without missing additional PCA (90% sensitivity). These data provide additional evidence for clinical advantages of equimolar-response over nonequimolar-response PSA assay formats.
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Blijenberg BG, Yurdakul G, Van Zelst BD, Bangma CH, Wildhagen MF, Schröder FH. Discordant performance of assays for free and total prostate-specific antigen in relation to the early detection of prostate cancer. BJU Int 2001; 88:545-50. [PMID: 11678748 DOI: 10.1046/j.1464-410x.2001.02374.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the value of applying rigid threshold values in interpreting prostate specific antigen (PSA) results, by selecting and comparing five current methods for measuring free and total PSA. MATERIALS AND METHODS Samples taken from an ongoing screening study for prostate cancer (total PSA by Tandem-E assay, 17 334 participants; biopsy criterion a PSA of 3.0 microg/L, 4 464 men) from men with a total PSA of 1.0-6.0 microg/L were measured for free and total PSA using the Access, Immulite, Elecsys and Prostatus analysis kits, in two patient groups, i.e. with prostate cancer or no evidence of disease. RESULTS Both patient groups had equal means for total PSA but not for free PSA. In all, 360 samples from men with cancer and 96 from men with no evidence of disease were analysed. All methods applied to both groups deviated statistically significantly from the Tandem-E result for total PSA, except for the Access kit. There was a close correlation among all the methods (correlation coefficients of 0.89-0.97). There were very discordant results for the combination of the Tandem-E vs Prostatus (8% difference), representing 315 participants at a threshold of 3.0 microg/L. For free PSA (free/total PSA) the situation was worse, with extreme differences of 32% and 36% for both patient groups (Elecsys vs Access). CONCLUSIONS Depending on the threshold value applied as an indication for biopsy, when using the total PSA alone or combined with the free/total PSA, care is needed in interpreting patient groups because of the discordance among PSA assays.
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Affiliation(s)
- B G Blijenberg
- Department of Clinical Chemistry and Urology, University Hospital Rotterdam, The Netherlands.
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Semjonow A, De Angelis G, Oberpenning F, Schmid HP, Brandt B, Hertle L. The clinical impact of different assays for prostate specific antigen. BJU Int 2000; 86:590-7. [PMID: 10971300 DOI: 10.1046/j.1464-410x.2000.00858.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- A Semjonow
- Department of Urology and Institute of Clinical Chemistry and Laboratory Medicine, Westfälische Wilhelms-Universität, Münster, Germany.
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