BC is classified according to the presence of receptors into 4 major molecular subtypes (1, 2): luminal A (estrogen and/or progesterone receptor positive), luminal-HER (estrogen and/or progesterone receptor positive and HER2 positive), HER2 (human epidermal receptor 2 positive or enriched) and triple-negative (negative for these receptors) (3). This evidence concerns the gene PGR and breast cancer.