Hormones have been confirmed to be related to breast cancer, and 30% of these cases are responsive to therapies that involve altered hormones by ablation of the endocrine glands and the addition of hormone activators or inhibitors.[1] Among these hormones, progesterone, with its proliferative effects, has been proposed to be closely related to the development of breast cancer via its respective receptors, the progesterone receptor (PR), which has been confirmed to regulate mammary growth and development.[2, 3]. This evidence concerns the gene PGR and breast cancer.