Prophylactic mastectomy prevents breast cancer in women at risk

A new study provides more evidence that women with a moderately elevated risk of developing breast cancer can significantly reduce their risk by undergoing bilateral prophylactic mastectomy. The risk reduction in the current study was about 95%, although the underlying absolute risk was quite low.

The researchers point out in the March 14th Archives of Internal Medicine that the underlying absolute risk of breast cancer in most women who had both breasts removed prophylactically in the study was “modest” and the risk of dying from breast cancer was “small.” Dr. Ann M Geiger from Kaiser Permanente’s Center for Research and Evaluation in Pasadena, California, and colleagues note that their retrospective case-control study looked at women with an elevated breast cancer risk who were cared for in community practices rather than specialized referral centers.The results are based on 276 women who underwent bilateral prophylactic mastectomy at a mean age of 45 and a stratified random sample of 196 representing a population-based sample of 666,800 women who did not. Both groups were considered to be at elevated risk for breast cancer due to the presence of at least one risk factor, most commonly a family history of breast cancer, history of atypical hyperplasia, or one or more breast biopsies with benign findings. In the prophylactic mastectomy group, only one woman developed breast cancer (0.4%) during a mean follow up of 10.3 years compared with an estimated 26,800 (4.0%) of 666,800 women who did not have the procedure and were followed for a mean of 6.2 years.In analyses stratified by birth, the researchers found that the hazard ratio for breast cancer after bilateral prophylactic mastectomy was 0.005. No woman who had both breasts removed died of breast cancer versus a calculated 0.2% of women who did not have the procedure. “Our results suggest a clinically meaningful reduction in breast cancer risk after bilateral prophylactic mastectomy,” the investigators write in their report. “However, the absolute underlying risk of breast cancer and death from breast cancer was low.” “Prophylactic mastectomy appears to prevent breast cancer but also carries a risk of complications and may impact a woman’s psychological health,” Dr. Geiger told Reuters Health. Women may alternatively opt to manage their risk with “tamoxifen, prophylactic oophorectomy, regular mammograms, and possibly MRI,” she said. (Source: Arch Intern Med 2005;165:516-520: Reuters Health: Oncolink: March 2005.)