(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 February 11 in BMJ.

Kelly Metcalfe, MD, 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% (95% confidence interval [CI], 83 to 93%) for those who had bilateral mastectomy and 66% (95 percent CI, 59 to 73%) 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% less likely to die from breast cancer (hazard ratio [HR], 0.52; 95% CI, 0.29–0.93; 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% CI, 0.34–1.06; P=0.08).

“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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