Results: RRSO was not associated with a significant reduction in the PBC risk (RR = 0.84, 95%CI: 0.59–1.21) or CBC risk (RR = 0.95, 95%CI: 0.65–1.39) in BRCA1 and BRCA2 carriers combined but was associated with reduced BC-specific mortality in BC-affected BRCA1 and BRCA2 carriers combined (RR = 0.26, 95%CI: 0.18–0.39). This evidence concerns the gene BRCA1 and breast cancer.