PSA Standardization

The Clinical Difference

October 2009

In the NPCC (National Prostate Cancer Coalition) grass-roots screening study performed in Chicago, 1916 men (approximately half of who were Caucasian) were compared using the Access which uses Hybritech standard and Siemens Bayer Centaur which is a WHO standard.  The findings of the study show a negative bias of greater than 20% in the Centaur values. Using a PSA threshold of 2.5 ng/mL, biopsy would have been recommended for 94 (5%) men using one assay (the Hybritech) but not the other (the Centaur).  At 4.0 ng/mL biopsy would have been recommended for 87 men (or 4.5%) using the Hybritech assay but not the Centaur.  This is in close agreement with the study on the previous slide, where it was found that 4.6% of men would not have been recommended for biopsy.

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The Clinical Difference

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Jump to section:

• 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?