Interestingly, in the subgroup of patients with ER positive BC who received chemotherapy and HER2 targeted therapy, those tumours that were IHC 3+ showed the highest pCR rate (58%) compared to 14% in the IHC 2+/ISH amplified tumours (Groups 1 and 3) (or 15% if Group 2 was included; combined Groups 1, 2 and 3). This evidence concerns the gene ERBB2 and breast cancer.