Effect of Finasteride on Prostate-Specific Antigen

D'Amico and Roehrborn conducted a prospective, double-blind, placebo-controlled, multicentre, randomised trial and found that 1 mg/day finasteride (Propecia) significantly lowers serum prostate-specific antigen (PSA) concentrations by 40% in men aged 40-49 years and by 50% in men aged 50-60 years within 48 weeks. The placebo group showed no change or an increase in serum PSA concentrations. The study suggests that the same effect on serum PSA is achieved with 1 mg/day finasteride as with 5 mg/day finasteride (Proscar), which is used for benign prostatic hyperplasia. The findings imply that for men taking 1 mg/day finasteride, PSA concentrations should be doubled when making clinical judgments for prostate biopsies. The study also highlights the need for clinicians to adjust PSA cutoffs and velocities for patients on low doses of 5α-reductase inhibitors. However, the study does not address the long-term effects beyond 48 weeks and acknowledges the potential for overestimation of PSA, leading to unnecessary biopsies.