The management of early-stage and metastatic triple-negative breast cancer: a review.

Triple-negative breast cancer (TNBC), defined as lacking expression of the estrogen receptor, progesterone receptor, and HER2, comprises approximately 15% of incident breast cancers and is over-represented among those with metastatic disease. There are several biologically distinct subtypes within TNBC. Although the incidence of BRCA mutations across all subsets of breast cancer is low, BRCA mutations are more common among those with TNBC and may have therapeutic implications. The general principles guiding the use of chemotherapy and radiation therapy do not differ dramatically between early-stage TNBC and non-TNBC.