According to the molecular characteristics, such as hormone receptors (HR) and human epidermal growth factor receptor 2 (HER2) expression status, breast cancer can be divided into four molecular subtypes: luminal A (HR+/HER2-), luminal B (HR+/HER2+), HER2-positive and triple-negative (HR-/HER2-). This evidence concerns the gene ERBB2 and breast carcinoma.