In the setting where the ongoing evolution of management of the axilla in breast cancer is being driven by better understanding of different sub-types of the disease, and of how these respond to chemotherapy, here we discuss management of the axilla in breast cancer patients who present with T1 or T2 N1 disease, while making the distinction between triple negative and HER2 positive tumors as one group, and hormone receptor positive/HER2 negative tumors as a second group. This evidence concerns the gene ERBB2 and breast carcinoma.