It is classified into 4 major molecular subtypes according to hormone receptor (HR), growth factor receptor expression, and/or extra copies of the human epidermal growth factor receptor 2 HER2 gene (also called ERBB2): luminal A (HR+/HER2−); HER2+; luminal B (HR+/HER2+); triple negative (triple-negative breast cancer TNBC; HR−/HER2−). This evidence concerns the gene ERBB2 and triple-negative breast carcinoma.