Since the first study by Sorlie and colleagues in 2003, knowledge about genetic, epigenetic and endogenous and exogenous factors associated with the five subtypes of breast cancers (Luminal A, Luminal B, HER2-enriched, Basal-like and Claudin-low) and their associated aberrant signaling pathways extensively increased and become extremely complex. This evidence concerns the gene ERBB2 and breast cancer.