Depending on the molecular characteristics, breast cancer is broadly classified into four types: (i) luminal A (ii) luminal B, (iii) human epidermal growth factor receptor 2 (HER2)-positive, (with overexpressed HER2 and negative estragon and progesterone receptors), and (iv) basal-like breast cancer (also known as hormone and HER2 negative or triple-negative breast cancer (TNBC)) [3,9]. This evidence concerns the gene PGR and breast cancer.