Absence of adjuvant chemotherapy was the most powerful factor that was linked to a dramatic decline in survival for patients with breast cancer with the pathogenic variants of BRCA1 and BRCA2. There was a negligible decline in mortality among carriers of BRCA1 and BRCA2 with TN breast cancer who received no chemotherapy and underwent any secondary risk–reducing strategy compared with surveillance. This evidence concerns the gene BRCA2 and breast cancer.