Small survival benefit for women who opt for contralateral prophylactic mastectomy

Among breast cancer patients, surgical removal of the opposite breast is associated with a small increase in 5-year survival, specifically for younger women with early-stage, estrogen-receptor negative tumors, according to a study published online February 25 in the Journal of the National Cancer Institute.

To prevent subsequent breast cancer, some women with cancer in one breast will have the other breast surgically removed. This study was undertaken because it is unknown if this treatment increases a woman's lifespan.

To determine this, Isabelle Bedrosian, M.D., and George J. Chang, M.D., of the University of Texas M. D. Anderson Cancer Center in Houston, and their research team used data from the Surveillance, Epidemiology, and End Results database, identifying 107,106 women with breast cancer who had undergone mastectomy between 1998 and 2003 and a subset of 8,902 women who also underwent contralateral prophylactic mastectomy during the same period. The associations of contralateral prophylactic mastectomy on breast cancer-specific survival were estimated, with further analyses by age, disease stage, and estrogen receptor status.

Improved breast cancer survival was observed mainly among younger women (aged 18-49 years) with early-stage (I-II), estrogen receptor-negative breast cancer. Among this subset of women who comprise < 10% of the study population, contralateral prophylactic mastectomy was associated with a nearly 5% increase in the 5-year breast cancer-specific survival rate, a small improvement, according to the authors. however, for the majority of women with breast cancer, no clear breast-cancer specific survival benefit was observed.

"Our observation that the association between contralateral prophylactic mastectomy and survival is most relevant among young women with early-stage ER-negative breast cancer is consistent with the survival benefit of contralateral prophylactic mastectomy being inversely related to the risk of death from the index cancer and directly related to the cumulative lifetime risk of death from a contralateral breast cancer event," the authors write.