Health Canada is warning that popular medications used to treat baldness and enlarged prostates may put men at a slightly increased risk of breast cancer.
The health agency said Thursday it's updating the labelling for generic finasteride medications to include information about rare reports of breast cancer in men.
Finasteride is a prescription drug sold in Canada under two brand names: Propecia and Proscar. Generic finasteride products are also available.
Propecia (1 mg finasteride tablets) is used for the treatment of male pattern hair loss. Proscar (5 mg finasteride) is used in the treatment and control of benign prostatic hyperplasia (BPH), or a non-cancerous enlarged prostate.
Male breast cancer has been reported in a small number of patients worldwide with both the 1 mg and 5 mg formulations of finasteride, though most of the reports have been in association with the 5mg formulation.
The labelling 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, Health Canada said.
The agency says it's not clear what role finasteride might play in breast cancer.
"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 Health Canada notice said.
Patients taking finasteride should report any changes in their breasts to their doctor. Changes might include breast enlargement, lumps, tenderness, pain or nipple discharge.
Patients with questions or concerns about their finasteride treatment should talk to their doctors, Health Canada advises.
