ERBB2 and breast cancer: Gallen International Breast Cancer Conference in 2013, Goldhirsch et al. highlighted a new definition of breast cancer subtypes: Luminal A and B (ER/PR+, HER2−, Ki67+), HER2+ B2 (ER/PR+, HER2 overexpression) HER2 overexpression (ER/PR−, HER2 overexpression), basal-like TNBC (ER/PR−, HER2−) and other special sub-groups [2].