FREE-TO-TOTAL PROSTATE-SPECIFIC ANTIGEN SERUM CONCENTRATIONS IN PATIENTS WITH PROSTATE-CANCER AND BENIGN PROSTATIC HYPERPLASIA

Objective To determine whether the proportion of total serum prostate- specific antigen (tPSA) which is unbound or free (free PSA) offers a b etter discriminant for the detection of patients with prostate cancer (CaP) and those with benign prostatic hyperplasia (BPH) than does seru m tPSA alone. Patients and methods In a retrospective analysis, the pr oportion of free PSA was determined in the sera of 60 patients with hi stologically confirmed localized (n = 39; pT1-3NoMo) and metastatic (n = 21; T2-4NxM+) CaP and 45 patients with BPH. Forty patients with uro lithiasis served as a control group. Serum levels of free and total PS A were determined using a chemiluminescent enzyme immunoassay. Results Patients with CaP had a lower percentage of free PSA (localized CaP m edian 8.8%; metastatic CaP median 7.1%) than patients with BPH (median 19.5%) and those with urolithiasis (median 18.8%; P < 0.001). The per centage of free PSA did not differ significantly between patients with clinically localized and metastatic disease. Conclusion The determina tion of the proportion of free PSA enhanced the discrimination between BPH and CaP and may reduce the number of unnecessary biopsies in pati ents with an elevated PSA. The results warrant further investigations in a broader population to improve the clinical use of serum PSA as a tumour marker for discriminating patients with an early, potentially c urable CaP from men with BPH.