PSA Standardization

Clinical Differences in PSA Screening¹⁴

October 2009

In a study from 2004 that was one of the first clinical reports of the impact of PSA standardization, over 2000 men were tested with the Hybritech assay and two other WHO standardized assays.  The study found that the WHO assays yielded results that were 23% lower.  Using a cutoff of PSA greater than 4.0 ng/mL, 57 patients (2.5%) would have been candidates for biopsy based on Access but not Centaur data. If a lower cutoff of PSA greater than 2.5 ng/mL had been used, this number would have increased to 107 patients (4.6%). If all men who had a PSA greater than 2.5 ng/mL were considered, 19% of those individuals would have a PSA that was at or above the 4.0 ng/mL cut-off.  This represents a “high prevalence of cancer” group and is dramatically similar to the 18% figure derived from the data seen on the previous slide.

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• Introduction
• Elevated PSA Result on Screening
• Reasons for Ordering PSA¹
• PSA Screening in the News
• Recommendations for Screening
• Arguments for Screening for Prostate Cancer
• Recommendations for Not Screening
• Arguments Against Screening for Prostate Cancer
• PSA Sensitivity and Specificity
• High-Grade Prostate Cancer is Not Rare When PSA =4.0 ng/mL⁶
• Increase Specificity Using PSA Velocity⁸
• Optimizing Clinical Sensitivity and Specificity: Age/Ethnic Reference Intervals^9,10
• Utilization of Free/Total PSA Ratio¹¹
• Why Aren't PSA Results Interchangeable?
• Development of PSA Standards
• Development of PSA Standards
• Effect of Analytical Bias on Classification Based on Fixed Criteria
• Analytical Difference: Results per 1000 Patients Tested¹³
• Hybritech vs. WHO Standardized Assays^12,14
• Analytical Differences¹⁵
• CAP Proficiency Testing
• WHO 96/670 Total PSA Preparations¹⁶
• WHO Calibration/Concordance at 3.1 ng/mL Cutoff⁵
• WHO Calibration/Concordance at 3.1 ng/mL Cutoff⁵
• WHO Calibration/Concordance at 4.0 ng/mL Cutoff⁵
• Clinical Differences in PSA Screening¹⁴
• The Clinical Difference
• Fixed Thresholds Produce Problems for Biopsy Recommendations
• Effect on "Watchful Waiting"
• Effect on "Watchful Waiting"
• Adding Biological Variability into the Mix
• Futures in Prostate Cancer Testing?
• PSA Testing at Mayo
• Conclusions
• References
• References
• Questions?