The general breast cancer population risk of contralateral breast cancer for women with a diagnosis of unilateral cancer is less than 10% at 25 years from initial diagnosis.19 In contrast, we estimated the risk to be 21.3% at 10 years and nearly 50% at 20 years for patients with breast cancer who had a pathogenic BRCA1/2 variant. This evidence concerns the gene BRCA1 and cancer.