It is noteworthy to mention that the term TNBC refers to the immunohistochemical description of the tumor (ER−, PR−, HER2−); while basal-like BC is defined from its gene expression signature and refers to a subset of TNBCs that express other markers of basal/myoepithelial cells such as basal cytokeratins (CK5/6, CK14 and CK17), vimentin, and epidermal growth factor receptor (EGFR). The gene discussed is ESR1; the disease is breast cancer.