Among the different types of breast cancers, tumors that are immunohistochemically characterized as estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and human epidermal growth factor receptor 2 (HER2)-negative are classified as triple-receptor negative breast cancers (TNBCs), and they account for 15–20% of all breast cancers [2]. This evidence concerns the gene PGR and breast cancer.