Molecular Testing in Breast Cancer.

Molecular testing for genetic and genomic variation has become an integral part of breast cancer management. Patients with a family history of breast cancer or other tumors, bilateral breast cancers, or early-onset breast cancers warrant genetic testing to determine whether a hereditary cancer syndrome is present. The availability of PARP inhibitors-drugs that are selectively active in BRCA1/2-associated breast cancers-has created the need for hereditary cancer testing for all patients diagnosed with advanced breast cancer.