Unlike the estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2) positive subtype, the biology of TNBC includes a high proliferation activity, a high degree of immune infiltration, basal-like or mesenchymal phenotypes, and insufficient homologous recombination (Denkert et al., 2017); its characteristics, including the risk factors, molecular and pathological characteristics, disease course, and sensitivity to chemotherapy, are distinct from those of other breast cancer subtypes (Borri and Granaglia, 2020). This evidence concerns the gene ESR1 and breast cancer.