Effect of Dutasteride on the Risk of Prostate Cancer

Dutasteride, an inhibitor of 5α-reductase in the prostate, was tested in a large, randomized trial to determine its ability to prevent prostate cancer. Over the 4 years of the trial, dutasteride, as compared with placebo, reduced the relative risk of biopsy-detected prostate cancer by 23%. The reduction was limited mainly to tumors with Gleason scores of 5 or 6; by year 4, there were 12 tumors with Gleason scores of 8 to 10 in the dutasteride group but only 1 in the placebo group. Dutasteride, an inhibitor of 5α-reductase in the prostate, reduced the relative risk of biopsy-detected prostate cancer by 23%; however, the reduction was limited mainly to tumors with Gleason scores of 5 or 6. The 5α-reductase inhibitors that are used to treat benign prostatic hyperplasia block the conversion of testosterone to dihydrotestosterone and may reduce the risk of prostate cancer. 1 The results of the Prostate Cancer Prevention Trial showed that finasteride, as compared with placebo, reduced the risk of prostate cancer by 25%, but among the tumors that were detected, there was a 27% increase in the number of those that had Gleason scores of 7 to 10. 2 (The Gleason score is the sum of the two most common histologic patterns or grades in a prostate tumor, each of which is graded on a . . .