INCREASED DISCRIMINATION BETWEEN BENIGN PROSTATIC HYPERPLASIA AND PROSTATE-CANCER THROUGH MEASUREMENT OF PERCENTAGE FREE PSA

Objective: The value of Prostate-Specific Antigen (PSA) for the early detection of Prostate Cancer (CaP) is contraversial due to an apprecia ble false positive rate causing unnecessary biopsies. As PSA exits in both free and bound forms the percentage of free PSA was found to be l ower in CaP than in Benign Prostatic Hyperplasia (BPH). We investigate d whether the percentage of free PSA offers better discrimination on t he detection of CaP. Material and Methods: In a retrospective analysis the percentage of free PSA was determined in the sera of 50 consecuti ve patients with histologically proven BPH (n=30) and clinically local ised CaP without metastases (n=20; pT1-3 No Mo). Serum levels of free PSA and total PSA were determined employing a chemiluminescent enzyme immunoassay. Results: Patients with CaP demonstrated a lower percentag e of free PSA (median: 8.5, range: 2.7-24.5) than patients with BPH (m edian: 22.35, range: 8.9-66.7). (p <0.001). Conclusion: Determination of percentage of free PSA enhances the discrimination between BPH and CaP and may reduce the number of unnecessary biopsies in patients with elevated PSA.