PURPOSE: Reported prostate-specific antigen (PSA) values may differ substantially between assays with the Hybritech and World Health Organization (WHO) standardization.
[-2]proPSA (p2PSA) and the Beckman Coulter prostate health index (phi) are newly approved serum markers, which are associated with prostate cancer risk and aggressiveness. Our objective was to study the influence of assay standardization on these markers.
MATERIALS AND METHODS: PSA, % free PSA (%fPSA), and p2PSA were measured using the Hybritech calibration in 892 men undergoing prostate biopsy from a prospective multicenter study. Phi was calculated as: [p2PSA/ fPSA) x (square root of PSA)]. Performance characteristics of phi for prostate cancer detection were then determined using re-calculated WHO calibration PSA values.
RESULTS: The median phi was significantly higher in men with prostate cancer compared to those with negative biopsies using the WHO values (47.4 vs 39.8, p< 0.001). Phi offered improved discrimination of prostate cancer detection on biopsy (AUC 0.704) compared to %fPSA or total PSA using the WHO calibration.
CONCLUSIONS: Phi can be calculated using Hybritech or WHO standardized assays, and significantly improved the prediction of biopsy outcome over %fPSA or PSA alone.
Loeb S, Sokoll LJ, Broyles DL, Bangma CH, van Schaik RH, Klee GG, Wei JT, Sanda MG, Partin AW, Slawin KM, Marks LS, Mizrahi IA, Shin SS, Cruz AB, Chan DW, Roberts WL, Catalona WJ. Are you the author?
Department of Urology, NYU Langone Medical Center, New York, New York.
Reference: J Urol. 2012 Nov 30. pii: S0022-5347(12)05770-9.