ESR1 and breast cancer: As a result, germline PV carriers have an increased risk of ovarian cancer and breast cancer, particularly estrogen receptor (ER)–negative breast cancer.1,2,3,4,5,6,7,8 In this regard, germline PVs in RAD51C/D are found in 0.3% of patients with breast cancer and 1% of patients with ovarian cancer.1,2,9,10,11