(HealthDay News) — Women with BRCA-associated early-stage breast cancer who receive bilateral mastectomy are less likely to die from breast cancer than those who receive a unilateral mastectomy, according to research published Feb. 11 in BMJ.

Kelly Metcalfe, M.D., of the University of Toronto, and colleagues performed a retrospective analysis of data for 390 women, carriers of the BRCA1 or BRCA2 mutations, who underwent unilateral mastectomy or bilateral mastectomy (181 patients) as initial treatment for stage I or II breast cancer.

The researchers found that, at 20 years (median follow-up time, 14.3 years), the survival rate for women with hereditary breast cancer was 88 percent (95 percent confidence interval [CI], 83 to 93 percent) for those who had bilateral mastectomy and 66 percent (95 percent CI, 59 to 73 percent) for those who had unilateral mastectomy. According to multivariable analysis, women with hereditary breast cancer who received a mastectomy of the contralateral breast were 48 percent less likely to die from breast cancer (hazard ratio [HR], 0.52; 95 percent CI, 0.29 to 0.93; P = 0.03). According to propensity score-adjusted analysis of 79 matched pairs, bilateral mastectomy was not significantly associated with reduced risk of death from breast cancer (HR, 0.60; 95 percent CI, 0.34 to 1.06; P = 0.08).

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“Given the worse prognosis of BRCA1/2 associated breast cancers, the absence of mammary tissue after a contralateral mastectomy should translate into a reduction of breast cancer related deaths,” writes the author of an accompanying editorial. “Nevertheless, larger studies tackling this issue are needed.”

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