Molecular subtypes in breast cancer are first described by Perou et al. [9] according to a specific gene expression pattern and divided into four simple subtypes based on hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status: HR+/HER2−, HR+/HER2+, HR−/HER+, and triple negative (TN). This evidence concerns the gene ERBB2 and breast cancer.