ERBB2 and breast cancer: Gallen Breast Cancer Conference in 2013, BC surrogates intrinsic groups were consensually defined as luminal A—ER+, PR ≥ 20%, HER2− and Ki67 < 20%; luminal B HER2 negative—ER+, HER2−, PR < 20% and/or Ki67 > 20%; luminal B HER2 positive—ER+, HER2+; HER2 positive—HER2+; ER−, PR− and triple negative—ER−, PR−, HER2− [4].