ERBB2 and breast cancer: The definition of basal-like BC has changed throughout time and there is no commonly accepted basis to define it. The panel produced by Nielsen et al. is mostly followed in practice that these basal-like tumors are negative for hormone receptors and human epidermal growth receptor-2 (HER2) and positive for cytokeratin (CK) 5/6 or epidermal growth factor receptor [6].