Prostate cancer chemoprevention: What's the next step?

Further analysis of the REDUCE (Reduction by Dutasteride of Prostate Cancer Events) trial will help answer important questions and direct therapy.

REDUCE randomized high-risk men to the 5-alpha-reductase inhibitor (5-ARI) dutasteride (Avodart) or placebo. Men in the treatment arm showed a 23% reduction in the risk of developing prostate cancer versus the placebo arm (see, "Dutasteride shown to reduce prostate Ca in high-risk men").

REDUCE was well designed, and its findings validate those of the landmark Prostate Cancer Prevention Trial, or PCPT (N Engl J Med 2003; 349:215-24). The PCPT showed a similar (24.8%) reduction in prostate cancer in men receiving the 5-ARI finasteride (Proscar). Sexual side effects were more common in both trials' treatment arms.

The rate of Gleason 7 to 10 cancers proved to be a striking difference between the studies, occurring in 37% versus 22.2% of the treatment versus placebo arms of PCPT and 6.7% versus 6.8% of the treatment versus placebo arms of REDUCE. This finding raises multiple questions:

Collectively, these data provide strong evidence that hormonal manipulation with 5-ARIs reduces the relative risk of prostate cancer, but multiple questions remain. Further analysis of the REDUCE trial with longer follow-up and pathologic analysis will help us answer these questions and direct therapy.

Dr. Thrasher, a member of the Urology Times Editorial Council, is professor and chair of urology, University of Kansas Medical Center, Kansas City.