Accurate cut-off point for free to total prostate-specific antigen ratio used to improve differentiation of prostate cancer from benign prostate hyperplasia in Iranian population

ABSTRACT

Our aim was to determine a more predictive cut-off value for free to total prostate-specific antigen ratio [f/tPSA] to better differentiate prostate cancer [PCa] from benign prostate hyperplasia [BPH] in Iranian patients with serum PSA levels between 4 and 20 ng/mL. This study was performed on 332 men with serum tPSA level of 4 to 20 ng/mL. All patients underwent transrectal ultrasound guided biopsies. Serum levels of tPSA and fPSA were measured by Roche immunoassay Elecsys 2010. Relationship between f/tPSA and cases of PCa was determined. Prostate cancer detected in 49 [15%] patients. Incidence of PCa for serum tPSA level < l0ng/mL and serum tPSA level of 10.1 to 20 ng/ mL was 17 [6.7%] and 32 [39.5%], respectively. Mean f/tPSA value was significantly lower in PCa patients [0.12 +/- 0.01] than in benign histology group [0.16 +/- 0.03]. Among patients with serum PSA level of 4 to 10 ng/mL [n = 251], mean f/tPSA in benign histology group [n = 234] was 0.16 +/- 0.08 and in PCa group [n = 17] was 0.13 +/- 0.06 [P < .05]. For serum PSA level of 10.1 to 20 ng/mL [n = 81], mean f/tPSA in benign histology group [n = 49] was 0.16 +/- 0.08 and in PCa group [n = 32] was 0.12 +/- 0.05 [P < .05]. The cut-off value of 0.12 produced 76% sensitivity and 71% specificity, whereas the cut-off value of 0.14 yielded 83.5% sensitivity and 61% specificity. Determination of f/tPSA ratio improves differentiation of Pea from BPH. We recommend a cut-off value of 0.14 to be applied to Iranian patients