Basal-like breast carcinoma: a phenotypically distinct entity.

Gene microarray profiling of human breast carcinomas has recently categorized invasive breast carcinomas into 5 distinct subtypes; luminal A, luminal B, normal breastlike, human epithelial growth factor receptor 2 (HER2) overexpressing, and basal-like. Basal-like breast carcinomas are characterized by high expression of basal cytokeratins; low or absent expression of estrogen receptor, progesterone receptor, and HER2/neu; and expression of epidermal growth factor receptor (EGFR) and/or c-kit, and they are frequently associated with breast cancer 1 (BRCA1) mutations and poor clinical outcome. Recent studies have begun to provide insights into the molecular genetics, biology, morphology, and clinical outcome of this subtype of breast carcinoma. We reviewed the literature related to basal-like breast carcinomas to better understand this clinically significant subtype of breast carcinoma.