Prophylactic bilateral mastectomy: patterns of practice

Many women who are at an elevated risk of developing breast carcinoma choose prophylactic mastectomy to decrease their risk. We conducted a population-based study to review the indications for, and patterns of practice of prophylactic mastectomy in Ontario, Canada, since 1991.

A medical chart review was conducted at 33 hospitals that were identified as having conducted at least one prophylactic mastectomy. All bilateral mastectomy patients with no diagnosis of invasive or in situ breast carcinoma were eligible.

The number of prophylactic bilateral mastectomies performed varied from 6 to 19. The mean age of women undergoing prophylactic mastectomy was 43.5 years. Eighty percent of the women had prophylactic mastectomy performed because of a family history of breast carcinoma (89 of 99) or because of a known BRCA1 or BRCA2 mutation (10 of 99). Twenty percent of the women had no family history, but had the surgery for other benign breast conditions. Women with a family history of breast carcinoma were much more likely to have a total mastectomy (89%) than a subcutaneous mastectomy (11%). Sixty percent of the women had reconstructive surgery following mastectomy.

Prophylactic mastectomy is not performed on a large scale. The introduction of genetic testing for BRCA1 and BRCA2 has the potential to change the patterns of practice for prophylactic mastectomy.