
BRCA1 and BRCA2 occupy a central role in the repair of a specific type of damage to the DNA through a DNA repair pathway called homologous recombination repair (HRR). Multiple other genes (referred to as BRCA-related genes) also participate directly or indirectly in HRR. These genes include PALB2, BARD1, BRIP1, RAD50, RAD51C, RAD51D, RAD54L, ATM, ATR, ATRX, FANCONI anemia genes (e.g. FANCA, FANCB, FANCC), CHEK1, CHEK2, BLM, NBN, MRE11A, and others.
BRCA1, BRCA2 and BRCA-related genes are frequently mutated in multiple tumor types, especially breast, ovarian, pancreatic, and prostate cancers, and other malignancies. Mutations in these genes may be present in the germline (i.e., hereditary and detectable via genetic testing) or may be present in the tumor only, i.e., detected via testing of the tumor using institutional (such as Dana-Farber's OncoPanel), commercially available assays examining tumor DNA, or liquid biopsies, such as from Foundation Medicine or Gardant.
Approximately 10-15% of patients with ovarian, breast, pancreatic, and prostate cancers have germline (heritable) BRCA1/2 mutations, and another 15-30% of patients have somatic BRCA1/2 mutations or somatic alterations in BRCA-related genes. Tumors with mutations in BRCA and BRCA-related genes are particularly sensitive to treatments that cause damage to the DNA, such as platinum-based chemotherapy and targeted agents such as PARP inhibitors. Of note, PARP inhibitors induce a type of DNA damage that cannot be repaired in tumors with mutations in BRCA and BRCA-related genes, and are therefore particularly active against these tumors. PARP inhibitors are now FDA-approved for ovarian, breast, pancreatic, and prostate cancers and represent the first DNA repair targeted therapy approved for cancer patients.