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You may be familiar with finasteride (Proscar) and dutasteride (Avodart) as drugs used to treat benign prostatic hyperplasia (BPH), but studies have also looked at whether these two 5-alpha-reductase inhibitors could help prevent prostate cancer. Experts from the Food and Drug Administration’s Oncologic Drugs Advisory Committee evaluated this idea recently, and their conclusions appear in the New England Journal of Medicine.
The results of two large randomized, placebo-controlled trials—the Prostate Cancer Prevention Trial (PCPT, which used finasteride) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial–were at the center of the discussion. Both trials showed an overall reduction of 23 to 25 percent in prostate cancer diagnoses among men who took these drugs. However, there is more to the story.
The reduction in prostate cancer was seen only in low-grade cancer (Gleason scores of 6 or less), while there was an increased incidence of high-grade tumors (Gleason scores 8-10) associated with use of either of the two drugs. The increase was equal to one man receiving a diagnosis of high-grade prostate cancer for every 150 to 200 men treated long-term with dutasteride or finasteride.
The committee members considered factors such as PSA results and that the increased incidence of high-grade prostate cancer could be associated with a reduced prostate volume, but in the end, the members ruled neither of these factors had an effect on high-grade cancer incidence.
When the reduction in prostate cancer risk was examined, the committee members said because 80% of the low-grade Gleason scores met the criteria for very low-risk prostate cancer, the reduction was not clinically significant. Ultimately, the advisory committee concluded “finasteride and dutasteride do not have a favorable risk-benefit profile,” the FDA concurred, and the two 5-alpha reductase inhibitors did not get a green light to be prescribed to prevent prostate cancer.
Read more in our Prostate Cancer Health Center.
Theoret MR et al. The risks and benefits of 5α-reductase inhibitors for prostate-cancer prevention. New England Journal of Medicine 2011 Jul 14; 365(2): 97-99