Pros and cons of preventive bilateral mastectomies

Increasing numbers of women, who have been diagnosed with breast cancer in one breast, are opting for bilateral mastectomies to reduce the risk of a future second breast cancer. Until now, there have not been studies to demonstrate how helpful this strategy can be.

Of course there are women who opt for this surgery for medical reasons. Women who carry a BRCA gene may even have this surgery to prevent ever having breast cancer. Others, with the gene, opt for bilateral surgery after diagnosis. There are other women whose unique medical circumstances indicate the wisdom of this choice. Many women, however, make this decision without the recommendation of their surgeon and without complete information about how successful this strategy can be. Given that this is a choice that cannot be undone, it is extremely important that women are fully informed of their options, the likely consequences, and any information that may help them make the best choice for themselves and their futures.

For some time, there has been discussion about the importance of women understanding that, usually, having a mastectomy or bilateral mastectomies does not increase the chance of staying well after treatment. To simplify: cancer in the breast itself does not kill. It is the spreading of cancer to other parts of the body that is lethal.

Any surgery has risks. Choosing to have bilateral mastectomies, rather than one, extends the length of the operation itself and pretty much doubles the other risks related to possible infection, problems with healing, or dissatisfaction with the outcome. Some women strongly want to be even or matched and understand that going flat or having reconstruction on both sides will make that possible.

For the first time, a new study published in Cancer measures the magnitude of this risk reduction. Researchers used data from the Surveillance, Epidemiology, and End Results (SEER) program, considering all women who had been diagnosed with Stage 0 to Stage III breast cancer in California between 1998 and 2015. These women had been treated either with a lumpectomy and radiation or a single mastectomy. The authors looked both at the numbers of deaths from breast cancer and the later development of second cancers in the other breast. More than 245,000 women were included in the study.

Here are their stated conclusions: Bilateral mastectomies (BLM) may reduce second breast cancer risk by 34 to 43 cases per 10,000 person‐years compared with other surgical procedures, but is not associated with a lower risk of death. Second breast cancers are rare, and their reduction should be weighed against the harms associated with BLM.

No one can make a decision for someone else. There certainly are women who will look at these numbers and feel that 34-43 cases is enough of a reason to lose both breasts. There are others who will hesitate at the quite small possibility of a second cancer. And again, there are other reasons that women choose bilateral mastectomies. This study gives us information about one consideration and should be part of all newly diagnosed women's conversation with their doctors.