BIOLOGIC VARIABILITY OF PROSTATE-SPECIFIC ANTIGEN AND ITS USEFULNESS AS A MARKER FOR PROSTATE-CANCER - EFFECTS OF FINASTERIDE

Objectives. The effects of finasteride on prostate-specific antigen (P SA) variability and usefulness in prostate cancer detection were exami ned. Methods. Percent change and crossover of PSA levels between the l ow (1.0 to 3.9 ng/mL) and high (4.0 to 10.0 ng/mL) ranges were evaluat ed in 72 men with benign prostatic hyperplasia (BPH) and 77 men with b oth BPH and prostate cancer (PCa) treated with finasteride or placebo for 6 months. Patients with PCa were studied as a model for evaluating the effects on PSA levels in patients with BPH and latent PCa. As rec ommended on the product label, PSA levels for finasteride-treated pati ents were doubled for interpretation. Results. In patients with BPH, m ost placebo-and finasteride-treated patients with low PSA levels at ba seline had subsequent PSA levels below 4.0 ng/mL throughout the study. Among patients with high baseline PSA levels, only 1 of 17 finasterid e-treated patients, compared with 8 of 13 placebo-treated patients, cr ossed into the low range. In the BPH/PCa study, most placebo-treated p atients maintained PSA levels in the same range (15 of 19 less than 4. 0 ng/mL; 14 of 16 greater than 4.0 ng/mL). Almost one third of finaste ride-treated patients with low PSA levels at baseline crossed into the high range (8 of 22), whereas most patients with high PSA levels at b aseline were not masked with treatment, with PSA levels remaining high (12 of 15). Conclusions. PSA levels cross between the low and high PS A ranges in both finasteride- and placebo-treated patients with BPH an d those with both BPH and PCa. Doubling the PSA levels in finasteride- treated patients allows appropriate interpretation of PSA values and d oes not mask the detection of PCa. (C) 1998, Elsevier Science Inc. All rights reserved.