Risk-reducing salpingo-oophorectomy and breast cancer incidence among BRCA-mutation carriers.

Abstract

10548 Background: Uncertainty exists with regard to the role of bilateral salpingo-oophorectomy in altering the risk of breast cancer in BRCA-mutation carriers. Methods: Included were 1645 healthy Jewish Israeli BRCA1/2 -mutation carriers from a single center without prophylactic mastectomy. Carriers with and without risk-reducing bilateral salpingo-oophorectomy (RRBSO) were matched according to BRCA-mutation type (BRCA1 vs. BRCA2) and year of birth (±1 year). Hormonal and reproductive variables were compared and incidence of breast cancer recorded. Association between RRBSO and breast cancer was studied. Results: Seventy-seven and 50 matched-pairs had BRCA1 and BRCA2 mutation respectively. Fifty-two carriers had breast cancer, 21 in RRBSO-group and 31 in no- RRBSO group, with no statistically significant difference. When analysing each mutation group separately, stratified by age at surgery, no association between RRBSO and breast cancer incidence was found among BRCA1-mutation carriers. However, in BRCA2 mutation carriers, RRBSO was associated with a statistically significant decreased overall incidence of breast cancer, HR = 0.2 (confidence interval 0.44-0.913, p = 0.038). Breast cancer incidence was lower after 5, 10,15 and 20 years in BRCA2-mutation carriers with RRBSO compared to no-RRBSO. Age at menarche, age at surgery, parity and oral contraceptive use were not significant risk factors for breast cancer. Hormone replacement therapy was used by 62 mutation carriers, 52 in the RRBSO group and 10 in the no-RRBSO group, and its use did not alter breast cancer risk (p = 0.463). Conclusions: According to our findings, RRBSO is associated with a reduced risk of breast cancer only in BRCA2 mutation carriers, regardless of HRT use.