Efficacy and Safety of Dutasteride on Prostate Cancer Risk Reduction in Asian Men: The Results from the REDUCE Study

Objective: A post hoc analysis of Asian men in the REDUCE study was conducted to investigate whether the outcomes were in line with those of the overall population. Methods: REDUCE was a 4-year international, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. Inclusion criteria were men between 50 and 75 years of age, a serum prostate-specific antigen level of 2.5-10.0 ng/ml (50-60 years) or 3.0-10.0 ng/ml (> 60 years), and a single, negative prostate biopsy (6-12 cores) within 6 months before enrollment. The primary endpoint was biopsy-detectable prostate cancer. This post hoc analysis included subjects who were recorded as Asian. Results: A total of 134 Asians, including 57 Japanese, were randomized to the study treatment. During the study period, the incidence of prostate cancer in the placebo and dutasteride groups was 19.6% (11/56) and 9.3% (5/54), respectively (relative risk reduction, 54%; 95% confidence intervals, -27 to 83%, P = 0.12), in the Asian subpopulation. Fewer tumors with the Gleason scores of 7-10 and 8-10 were detected among dutasteride-treated men. Although the incidences of drug-related sexual adverse events were higher in the dutasteride group, only in rare occasions did they lead to drug discontinuation. Conclusions: The incidence of prostate cancer in the dutasteride group was lower than that in the placebo group, although the difference was not significant. These results paralleled those for the overall population and support the value of dutasteride for prostate cancer risk reduction in Asian men with an increased risk of prostate cancer.