BRCA1 and breast cancer: BRCA1/2-mutated ovarian and breast cancers have high sensitivity to platinum chemotherapy and poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors because of defective DNA double-strand break repair.24-26 The US Food and Drug Administration has approved the PARP inhibitor olaparib for BRCA1/2-mutated advanced ovarian cancer.