Comparison of several combinations of free, complexed, and total PSA in the diagnosis of prostate cancer in patients with urologic symptoms.

Abstract Objectives To compare the diagnostic efficacy of prostate-specific antigen (PSA) and the PSA fractions (free PSA [fPSA] and complexed PSA [cPSA]) in the differential diagnosis between prostate cancer and benign prostatic hyperplasia. Methods We measured the serum levels of total PSA (tPSA; Hybritech and Bayer), fPSA (Hybritech), and cPSA (Bayer) in 72 patients with prostate cancer and 128 patients with benign prostatic hyperplasia. Results Receiver operating characteristic curves were used for comparison of these tests. The greatest area under the curve was observed for the fPSA/cPSA ratio and the fPSA/tPSA ratio (0.757 and 0.754, respectively). The substitution of the fPSA/tPSA ratio with the fPSA/cPSA ratio in the diagnostic scheme of prostate cancer improved the diagnostic accuracy, with similar sensitivity and an increment in specificity (41% versus 45%). Conclusions The fPSA/cPSA ratio ensures a reduction in negative biopsies in the PSA gray zone. We suggest substituting the fPSA/tPSA ratio with the fPSA/cPSA ratio for patients with a PSA level between 4 and 10 ng/mL.