The four-year REDUCE (REduction by DUtasteride of prostate Cancer Events) clinical study evaluated prostate cancer risk reduction in men taking dutasteride, a 5-alpha-reductase inhibitor (5ARI) typically used to treat enlarged prostate. REDUCE results showed that dutasteride decreased the risk of biopsy detectable prostate cancer by 22.8 percent compared to a placebo group, but concerns remained about the drug's effectiveness. Results from a follow-up study are now published in The Journal of Urology®.
"The REDUCE Follow-up Study was a two-year observational follow-up of men who participated in the four-year REDUCE trial," says lead investigator Robert L. Grubb III, Associate Professor of Surgery (Urology), Washington University of Medicine in St. Louis, Missouri. "The primary objective was to collect data on the occurrence of new cases of prostate cancer for two years beyond REDUCE."
Nearly 2,800 men from the REDUCE study participated, representing extension safety and at-risk populations. In the original study, about half were treated with dutasteride and the remainder received a placebo.
Shortly after the REDUCE study's conclusion, Dr. Grubb and co-investigators followed participants with a clinic visit. They also conducted up to two annual telephone calls, collecting patient data on prostate cancer events, chronic medication use, prostate specific antigen levels, and serious adverse events. No drugs were administered and no additional biopsies were performed except those "for-cause" when clinically indicated.
Results showed that few new prostate cancers were detected during the two-year follow-up in either treatment group and no deaths were reported. However, the former dutasteride group produced double the number of cancers than the former placebo group (14 vs. 7). Investigators hypothesize that any prostate cancer that may have been suppressed by dutasteride during REDUCE was no longer being suppressed for those subjects who did not continue on 5ARI therapy. To some extent, observations during the follow-up study support this concept.