Risk-Reducing Oophorectomy and Breast Cancer Risk Across the Spectrum of Familial Risk.

Terry MB1,2, Daly MB3, Phillips KA4,5,6, Ma X1, Zeinomar N1, Leoce N1, Dite GS5, MacInnis RJ5,7, Chung WK2,8, Knight JA9,10, Southey MC11, Milne RL5,7, Goldgar D12, Giles GG7, Weideman PC5, Glendon G9; kConFab Investigators, Buchsbaum R13, Andrulis IL9,14, John EM15, Buys SS12, Hopper JL5.

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Abstract

There remains debate about whether risk-reducing salpingo-oophorectomy (RRSO), which reduces ovarian cancer risk, also reduces breast cancer risk. We examined the association between RRSO and breast cancer risk using a prospective cohort of 17 917 women unaffected with breast cancer at baseline (7.2% known carriers of BRCA1 or BRCA2 mutations). During a median follow-up of 10.7 years, 1046 women were diagnosed with incident breast cancer. Modeling RRSO as a time-varying exposure, there was no association with breast cancer risk overall (hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 0.87 to 1.24) or by tertiles of predicted absolute risk based on family history (HR = 0.68, 95% CI = 0.32 to 1.47, HR = 0.94, 95% CI = 0.70 to 1.26, and HR = 1.10, 95% CI = 0.88 to 1.39, for lowest, middle, and highest tertile of risk, respectively) or for BRCA1 and BRCA2 mutation carriers when examined separately. There was also no association after accounting for hormone therapy use after RRSO. These findings suggest that RRSO should not be considered efficacious for reducing breast cancer risk.