INCREASED DIFFERENTIATION BETWEEN PROSTAT E-CANCER AND BENIGN PROSTATIC HYPERPLASIA THROUGH MEASUREMENT OF THE PERCENTAGE OF FREE PROSTATE-SPECIFIC ANTIGEN

We investigated whether the free-to-total prostate-specific antigen (P SA) ratio (f-PSA/t-PSA ratio; i. e. percentage of free PSA) represents a better discriminator for the detection of cancer of the prostate (C aP). In a retrospective analysis, the persentage of free PSA was deter mined in the sera of 35 patients with histologically proven benign pro static hyperplasia (BPH) and 35 patients with clinically localized CaP . Patients with urolithiasis (n = 33) served as a control group. Serum levels of free PSA and total PSA were determined employing a chemilum inescent enzyme immunoassay. Patients with CaP demonstrated a lower pe rcentage of free PSA (median: 8.7) than patients with BPH (median: 20. 0; P < 0.001) and those with urolithiasis (median: 18.8; P < 0.001). D etermination of the percentage of free PSA enhances the differentiatio n between BPH and CaP and may reduce the number of unnecessary biopsie s in patients with an elevated PSA. Confirmation of our preliminary re sults is required.