A 2002 study of 11,847 women with a BRCA1 gene mutation demonstrated a two to three-fold higher risk for endometrial carcinoma, although many of these women were users of tamoxifen for treatment and/or prophylaxis of breast cancer, and tamoxifen alone could be a risk factor for endometrial carcinoma.20In another 2020 study of 1,350 BRCA1 and 1,259 mutated BRCA2, a higher risk for endometrial carcinoma was not identified, not even for serous carcinoma.21 This evidence concerns the gene BRCA1 and breast cancer.