Canadian agency: 5-ARI may be linked to male breast cancer risk

Health Canada is informing health care practitioners and patients of a labeling update for the 5-alpha-reductase inhibitor finasteride (Propecia, Proscar) to add safety information regarding rare reports of breast cancer in men.

Male breast cancer has been reported in a small number of patients worldwide with both the 1-mg (Propecia) and 5-mg (Proscar) formulations of finasteride, the latter of which is indicated for treatment of BPH. Most of the reports have been in association with the 5-mg formulation. Based on the currently available evidence, it is not known with certainty whether finasteride can cause breast cancer, nor can this possibility be ruled out at this point in time, according to a Health Canada press release.

Canadian labeling for Propecia, Proscar, and several of the generic finasteride products has already been updated to include information on the potential risk of male breast cancer, the press release said. Updates to the remaining generic drugs will follow.