MEASUREMENT OF PERCENT FREE PROSTATE-SPEC IFIC ANTIGEN - INCREASED DISCRIMINATION BETWEEN PROSTATE-CANCER AND BENIGN PROSTATIC HYPERPLASIA

In this retrospective analysis we investigated whether the free-to-tot al PSA ratio (f-PSA/t-PSA ratio; i.e. percent free PSA) offers a bette r discriminant for the detection of cancer of the prostate (CaP) in pa tients with serum PSA levels between 4 and 10 ng/mL. The percent free PSA was determined in sera of 26 patients with histologically proven B enign Prostatic Hyperplasia (BPH) and 24 patients with clinically loca lized Cap Patients with urolithiasis (N=30) served as a control group. Serum levels of free PSA and total PSA were determined employing a ch emiluminescent enzyme immunoassay. Patients with Cap demonstrated a lo wer percent free PSA (median: 9.2) than patients with BPH (median: 17. 9; p<0.001) and those with urolithiasis (median: 18.2; p<0.001). We co nclude that determination of percent free PSA enhances the discriminat ion between BPH and CaP and may reduce the number of unnecessary biops ies in patients with a PSA in the diagnostic gray zone. Confirmation o f our preliminary retrospective results in a prospective study is warr anted.