Prospective study on the performance of the prostate-specific antigen isoform P2PSA and its derivative prostate health index in prediction of prostate cancer in local Chinese men with total prostate-specific antigen levels of 4-10 ng/mL

Abstract

OBJECTIVES To evaluate the accuracy of the prostate-specific antigen isoform P2PSA and its derivatives including Prostate Health Index (PHI) in determining the presence of prostate cancer in prostate biopsies with serum total prostate-specific antigen (tPSA) at 4–10 ng/mL. METHODS This was a prospective cohort study involving two urology centers. Patients with tPSA at 4–10 ng/mL with a negative digital rectal examination who consented to prostate biopsy to detect underlying prostate cancer were recruited from March 2013 to March 2016. Their serum tPSA and P2PSA were checked before the biopsy and evaluated with respect to their prostate biopsy results. RESULTS Two hundred and forty-seven patients were recruited with cancer detected in 43 (17.4%) patients. %P2PSA and PHI were significantly higher in patients with cancer (P < 0.0001) whilst %fPSA and tPSA were similar between the two groups. ROC analysis showed the AUC for tPSA, %fPSA, %PSPSA and PHI to be 0.50, 0.58, 0.77 and 0.76 respectively. %P2PSA and PHI were the best predictor of underlying prostate cancer and were significantly better than tPSA (P < 0.0001 and 0.0005 respectively). At a sensitivity of 90%, PHI has the highest specificity (43.1%) amongst all the markers (tPSA: 7.4%, % fPSA: 27.0%, %P2PSA: 37.7%). When compared with tPSA, the use of the PHI would avoid 73(39%) of patients from unnecessary biopsies. CONCLUSIONS PHI is a superior marker to tPSA in detection of prostate cancer in our cohort of local Chinese men. Its use in addition to tPSA can improve its accuracy and aids in patient counseling regarding whether to proceed with prostate biopsies.