Finasteride and prostate cancer: a commentary.

Prostate cancer management has focused on early detection and treatment, but the prolonged development cycle of prostate cancer suggests that prevention may be a preferable approach. Finasteride and dutasteride, inhibitors of 5 -reductase, inhibit conversion of testosterone to dihydrotestosterone (a potent androgen) and have low toxicity, which makes them attractive chemopreventive agents. Both drugs have been proven successful in treating benign prostatic hyperplasia (BPH) and have been approved by the U.S. Food and Drug Administration (FDA) for this indication [1]. Lower doses of finasteride have also been approved for treatment of male pattern baldness [2]. There was great hope that they would be safe, easy, and effective chemoprevention agents against prostate cancer, but studies show otherwise. In this issue of The Oncologist, Kao and colleagues from Taiwan report on the most recent study that shows finasteride use was associated with an actual increase in risk of prostate cancer [3]. They identified 1,489 patients with cancer and BPH in the Taiwanese National Health Insurance registry and carefully matched three patients without cancer. The use of finasteride was associated with an increased risk of prostate and overall cancer (prostate cancer risk increased with an odds ratio of 1.9; overall cancer odds ratio was 1.5). Use of dutasteride was associated with no reduction in risk of prostate cancer and an increased risk of renal cancer. These disappointing results are in line with several other randomized trials investigating the use of these drugs for chemoprevention.