ERBB2 and neoplasm: It is generally categorized into five major subtypes based on the presence or absence of receptors expressed by tumor cells: luminal A (LumA), luminal B (LumB), HER2-overexpressing (or HER2-enriched or HER2+), triple negative breast cancer (TNBC), and basal-like and normal-like (or normal breast tissue-like) [19].