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 controversial due to an appreciable false positive rate causing unnecessary biopsies. As PSA exits in both free and bound forms the percentage of free PSA was found to be lower in CaP than in Benign Prostatic Hyperplasia (BPH). We investigated whether the percentage of free PSA offers better discrimination on the detection of CaP.

MATERIAL AND METHODS

In a retrospective analysis the percentage of free PSA was determined in the sera of 50 consecutive patients with histologically proven BPH (n = 30) and clinically localised 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 percentage of free PSA (median: 8.5, range: 2.7-24.5) than patients with BPH (median: 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.