Preventive Mastectomy Does Not Improve Five-Year Breast-Cancer Survival

Contralateral prophylactic mastectomy (CPM), a preventive mastectomy of a healthy breast, does not increase survival rates in most women with cancer in the other, according to a new study.

Researchers at the MD Anderson Cancer Center (Houston, TX, USA) analyzed the Surveillance, Epidemiology, and End Results (SEER) study database to identify 107,106 women with breast cancer who had undergone mastectomy for treatment between 1998 and 2003, and a subset of 8,902 women who also underwent CPM during the same period. Associations between predictor variables and the likelihood of undergoing CPM were evaluated, and risk-stratified adjusted survival analyses were performed for estrogen-receptor [ER] status, cancer stage, and age, using Cox regression.

The results showed that CPM was associated with improved disease-specific survival; but only patients younger than age 50 with early-stage cancer and estrogen-receptor-negative tumor experienced an improvement in their chance of five-year survival, a group that represents less than 10% of breast cancer patients. The study found that women in this group had a 4.8% increased chance of surviving five years, compared with women who did not have a preventive mastectomy. The researchers also found that women with ER-positive tumors in the absence of prophylactic mastectomy also had a lower overall risk for contralateral breast cancer than women with ER-negative tumors do. The study was published in the March 17, 2010, issue of the Journal of the National Cancer Institute (JNCI).

"We hope this study helps women make better decisions,” said lead author Isabelle Bedrosian, M.D., an assistant professor in MD Anderson's surgical oncology department. "The results provide some reassurance that perhaps a (preventive) mastectomy is not necessary, perhaps overly aggressive and perhaps a bit too much.”

Preventive mastectomy is the surgical removal of one or both breasts. Existing data suggest that preventive single or double mastectomy may significantly reduce the chance of developing breast cancer in moderate- and high-risk women, such as those with previous breast cancer, a family history of breast cancer, women who test positive for mutations in certain genes that increase the risk of breast cancer (such as the BRCA1 or BRCA2 gene), women with lobular carcinoma in situ, and women with diffuse and indeterminate breast microcalcifications.

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