Prostate Cancer Screening: Clinical Impact Of Who Calibration Of Beckman Coulter Access (R) Prostate-Specific Antigen Assays

Background: The goal of this study was to evaluate the clinical impact of using the same total prostate-specific antigen (tPSA) and free PSA (fPSA) assays calibrated with World Health Organization (WHO) materials or with Hybritech Tandem-R calibrator.Methods: From the initial correlation study that included 150 patients, the clinical impact of the WHO calibration was simulated using a large cohort (n = 4548) of referred patients. Interim reports of the European Study of Screening for Prostate Cancer (ERSPC) were used to evaluate the clinical outcomes of patients and the risk of prostate cancer (PCa).Results: WHO calibration of tPSA assays leads to a reduction of about 20% in measured results (tPSA WHO = 0.81 tPSA Hybritech + 0.04; fPSA WHO = 0.78 fPSA Hybritech + 0.00; %fPSA WHO = 0.92 %fPSA Hybritech + 0.00). The simulation showed that the WHO calibration is associated with a risk of missing 15% of PCa.Conclusions: The discrepancies between the two calibrations lead to significant clinical misinterpretation with decreased detection of PCa if tPSA cut-off thresholds are not adjusted. Clin Chem Lab Med 2010;48: 285-8.