Health Canada reports that male breast cancer has been reported in a small number of patients worldwide taking the prescription drug finasteride for male pattern baldness and enlarged prostate. Finasteride is sold under two brand names in Canada, Propecia (1 mg) to treat male-pattern hair loss and Proscar (5 mg), which is used for benign prostatic hyperplasia. Generic versions of both are also sold. Male breast cancer has been reported with both the 1 mg and 5 mg formulations of finasteride but most of the reports have been in association with the 5mg 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. The 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. Updates to the remaining generic drugs will follow. Healthcare professionals should encourage their patients taking finasteride to report any changes in their breasts, such as breast enlargement, lumps, tenderness, pain or nipple discharge.
