Double mastectomy to prevent cancer may result in small survival benefit

CANCER DIGEST – July 16, 2014 – Women without BRCA genetic mutations who have breast cancer in one breast and choose to have both breasts removed to prevent cancer in the opposite breast have an average increase in life expectancy ranging from 1 to 7 months depending on type and stage of cancer, according to a study published July 16 in the JNCI: Journal of the National Cancer Institute. 

Led by Pamela R. Portschy, researchers at the University of Minnesota, Minneapolis developed a statistical model to project survival outcomes of having the opposite breast removed or not for women with newly diagnosed stage I or II breast cancer. The model is based on data from the Surveillance, Epidemiology, and End Results (SEER) registry and large pooled-data studies of breast cancer. For women with stage I cancer the average gain in life expectancy from preventive mastectomy ranged from 1.6 months to 7 months. For those with stage II breast cancer the average gain was from less than a month to 3.5 months. The procedure was more beneficial for younger women and for those with stage I and estrogen receptor-negative breast cancer. Less than 8 percent of the women having the preventive surgery were projected to survive 20 years, which was no more than 1 percent higher than that projected for any of the women who did not have both breasts removed. Women with BRCA mutations were excluded from the analysis because they have a much higher risk of developing breast cancer in the opposite breast.

In an editorial in the same issue, Stephen G. Pauker and Mohamed Alseiari of the Division of Clinical Decision Making, Department of Medicine, Tufts Medical Center, Boston wrote that although the benefit may be small on average, the choice of preventive mastectomy may not be unreasonable for some women, depending on their family history or genetic background.

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