BRCA1 and breast cancer: Further, the cumulative lifetime risk of breast cancer for women who carry the BRCA1/2 genes was estimated to be 72% for women who carry the BRCA1 gene and 69% for women who carry the BRCA2 gene, and women who had either BRCA1 or BRCA2 mutations carried greater risk for developing breast cancer if they had a family history (5).