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The impact of oophorectomy on survival after breast cancer in BRCA1 and BRCA2 mutation carriers.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Oophorectomy is often recommended to women with BRCA-associated breast cancer in order to prevent a second primary breast cancer and ovarian cancer. However, it is unclear if oophorectomy has an impact on survival in women with BRCA-associated breast cancer. The objective of the current study was to estimate the impact of oophorectomy on survival from breast cancer for women with a BRCA1 or BRCA2 mutation Methods: 760 women with Stage I or Stage II breast cancer and a BRCA1 or BRCA2 mutation, between the ages 25 and 65, were followed for up to 20 years from diagnosis. The impact of oophorectomy on survival was evaluated in a Cox proportional hazards model, adjusting for age, gene (BRCA1 versus BRCA2), tumour stage, ER status and other treatments. Results: Of the 760 women, 455 had an oophorectomy, either prior to or after the diagnosis of breast cancer. The 20-year survival for the entire patient cohort was 74.3%. The un-adjusted hazard ratio for death associated with oophorectomy was 0.62 (95% CI: 0.42 to 0.90; p = 0.01) and the adjusted hazard ratio was 0.66 (95% CI 0.42 – 1.02; p = 0.06). The hazard ratio was 0.59 (95% CI: 0.34 – 1.01; p = 0.05) for BRCA1 carriers and was 0.81 (95% CI: 0.35 -1.85; p = 0.61) for BRCA2 carriers. The adjusted hazard ratio was 0.77 (95% CI 47 – 1.28; p = 0.29) for women diagnosed under age 50 and was 0.38 (95% CI: 0.12 to 1.15; p = 0.09) for women diagnosed over age 50. The hazard ratio was 1.21 (95% CI: 0.55 to 2.67; p = 0.65) for women with estrogen receptor-positive breast cancer and was 0.27 (95% CI: 0.11 to 0.67; p = 0.005) for women with estrogen receptor-negative breast cancer. Conclusions: Oophorectomy is associated with a decrease in mortality in women with early-stage breast cancer and a BRCA1 mutation. Women with estrogen receptor-negative breast cancer and a BRCA1 mutation should consider oophorectomy shortly after diagnosis as part of their treatment plan.