BRCA1/2 genes are crucial for DNA repair, with mutations increasing cancer risk. PARP inhibitors (PARPi) target these mutations, showing efficacy in BRCA1/2 mutated cancers and some BRCA wildtype tumors with HRD. FDA-approved PARPi include olaparib, rucaparib, and niraparib, used in ovarian, breast, and other cancers, despite potential hematologic toxicities.