To study if placebo-induced improvement in men with symptomatic benign prostatic hyperplasia (BPH) is maintained over 2 years, and to study the efficacy and safety from intervention with finasteride 5 mg for 24 months.

This was a multicenter, double-blind, placebo-controlled study involving 707 patients with moderate symptoms of BPH enrolled at 59 centers in five Scandinavian countries. Following enrollment and a 4-week single-blind placebo run-in period, patients were randomized to receive finasteride 5 mg once daily or placebo for 24 months. Urinary symptoms, urinary flow rate, prostate volume, postvoiding residual urinary volume, and serum concentrations of prostate-specific antigen together with laboratory safety parameters were measured at entry and at months 12 and 24. Interim physical and laboratory examinations were performed when indicated clinically.

In finasteride-treated patients the total symptom score improved throughout the study, with a significant difference between the two groups at 24 months (P ≤ 0.01), whereas in placebo-treated patients, there was an initial improvement in the symptom score but no change from baseline at 24 months.

The maximum urinary flow rate decreased in the placebo group, but improved in the finasteride group, resulting in a between-group difference of 1.8 mL/s at 24 months (P ≤ 0.01). The mean change in prostate volume was +12% in the placebo group versus −19% in the finasteride-treated group (P < 0.01). Finasteride was generally well tolerated throughout the 2-year study period.

The efficacy of therapy with finasteride 5 mg in improving both symptoms and maximum urinary flow rate and reducing prostate volume has been shown to be maintained during 24 months while patients receiving placebo experienced a return to baseline or deterioration of these parameters during the study. These results demonstrate that finasteride can reverse the natural progression of BPH.