Bilateral Mastectomy for Unilateral Breast Cancer: a Perplexing Trend

In the United States, there has been a trend towards the increased utilization of bilateral mastectomy for the treatment of unilateral breast cancer. Yet, breast conserving surgery rates have increased slightly, so it is among women choosing mastectomy that the use of bilateral mastectomy is increasing. Ironically, since about 1985, the risk of developing contralateral breast cancer has decreased, likely due to the widespread use of adjuvant systemic therapy for the treatment of early breast cancer. The increased utilization of bilateral mastectomy is therefore puzzling, and this article discusses factors that may account for this trend. Several observational studies have shown that bilateral mastectomy is associated with improved survival when compared to unilateral mastectomy. However, these associations are probably due to selection bias, and bilateral mastectomy is unlikely to have an independent effect in improving survival for the majority of women with unilateral breast cancer. Bilateral mastectomy might be indicated for women with a high risk of developing contralateral breast cancer, such as those with a history of mantle irradiation or mutations in the BRCA 1 or BRCA 2 genes, but it cannot be entirely justified in the majority of women with unilateral breast cancer.