(HealthDay News) — For women with stage I or II breast cancer without a BRCA mutation, contralateral prophylactic mastectomy (CPM) is associated with an absolute 20-year survival benefit of <1%, according to a study published online July 16 in the Journal of the National Cancer Institute.

Pamela R. Portschy, MD, from the University of Minnesota in Minneapolis, and colleagues developed a Markov model to simulate survival outcomes after CPM and no CPM among women with stage I or II breast cancer without a BRCA mutation. The magnitude of survival benefit was assessed among cohorts of women defined by age, estrogen receptor (ER) status, and stage of cancer.

The researchers found that, for women with stage I and stage II breast cancer, the predicted life expectancy gain from CPM ranged from 0.13–0.59 years and from 0.08–0.29 years, respectively. For women with stage I and stage II cancer, the absolute 20-year survival differences ranged from 0.56–0.94% and from 0.36–0.61%, respectively. Among younger women, stage I, and ER-negative breast cancer, CPM was more beneficial. In sensitivity analyses, the maximum 20-year survival difference with CPM was 1.45%.

“The absolute 20-year survival benefit from CPM was <1% among all age, ER status, and cancer stage groups,” the authors write.

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