Although finasteride and dutasteride lower overall risk of developing prostate cancer, they raise the chances of developing high-grade prostate cancer, a more serious form of the disease, the FDA (Food and Drug Administration) has announced. The Agency adds that the risk is low; but doctors need to be aware of this.

The FDA announced that all 5-alpha reductase inhibitor (5-ARI) medications will now have new safety information about the risk of developing high-grade prostate in their labeling, in the Warnings and Precautions section.

Examples of 5-ARI class medications include finasteride (Proscar, Propecia), dutasteride (Avodart), turosteride, bexlosteride and izonsteride. They are drugs with antiandrogenic activity and are used to treat benign prostatic hyperplasia (prostate gland enlargement) and androgenic alopecia (hair loss, baldness).

The FDA evaluated two randomized controlled trials – PCPT (the Prostate Cancer Prevention Trial), which compared finasteride 5mg against placebo for 7 years, and REDUCE (Reduction by Dutasteride of Prostate Cancer Events trial), which compared dutasteride 0.5 mg against placebo for 4 years. Both trials were measuring prostate cancer risk reduction in males aged 50+ years.

Even though both studies demonstrated an overall reduction in prostate cancer risk with both drugs, they also showed a higher risk of high-grade prostate cancer.

High-grade prostate cancer (Gleason score between 8 and 10) is the most deadly form of prostate cancer. It is an aggressive cancer which grows and spreads into surrounding areas rapidly. The cancer cells are large, very difficult to treat, and frequently reappear.

The FDA stresses that patients should talk to their doctors first before deciding on whether to change or stop any prescription medication.

Finasteride is marketed by Merck. Dutasteride is marketed by GlaxoSmithKline.

Written by Christian Nordqvist