Effects of finasteride on prostate volume and prostate-specific antigen.

BACKGROUND: Finasteride was introduced to treat patients with benign prostatic hyperplasia (BPH) recently, and it has shown its effects in reduction of prostate volume and decrease of prostate-specific antigen (PSA). We want to know how and how much does finasteride affect prostate volume as well as PSA and prostate-specific antigen density (PSAD), since PSA and PSAD are widely used as screening tools for early detection of prostate cancers. METHODS: Among 166 men with the diagnosis of BPH who received finasteride (5 mg/day) for 6 months, the serum PSA levels were measured. The prostate volumes before and after medication for a subgroup of 86 patients were measured by transrectal ultrasonography (TRUS). Paired t-test was used for the statistical analysis. The median percentage change in PSA of total 166 men and the median percentage changes in prostate volumes and PSAD of 86 men were also calculated. RESULTS: Among 166 men, the average serum PSA level was 2.48+/-2.02 ng/mL at baseline and 1.57+/-1.47 ng/mL at 6 months later. The median percentage change of serum PSA level was -44.26%. For 86 patients who underwent TRUS evaluation the average prostate volume changed from 39.83+/-21.10 mL to 33.62+/-20.52 mL. The median percentage change of prostatic volume was -17.80%. Also, the median percentage change in PSAD for these 86 patients after medication was -38.67%. CONCLUSIONS: Finasteride does decrease the serum PSA level and PSAD as well as prostate volume in men with BPH treated with it for 6 months. Physicians prescribing finasteride for patients with symptomatic BPH should always keep in mind its effect on PSA and PSAD levels in order not to miss potential prostate cancers.