ERBB2 and breast cancer: Of the 735 cases, 502 (68%) were luminal BC (estrogen and progesterone receptors positive/human epidermal growth factor receptor type 2 negative; HR+/HER2-), 137 (19%) were TNBC (HR−/HER2-) and 59 (8%) were HER2-enriched BC (HR−/HER2+).