ERBB2 and breast carcinoma: Breast cancers can be categorized into five separate subtypes: luminal A (ER+/PR+), luminal B (ER+/PR+/HER2 ± with high Ki-67), normal breast-like, HER2-positive (HER2-enriched), and triple-negative (ER−/PR−/HER2−; TNBC).