GnRHa can bind and activate GnRH receptors, but continuous administration or long-acting GnRH agonists overriding the physiologic pulsatile GnRH secretion leads to desensitization of pituitary GnRH receptor and the corresponding inhibition of gonadotrophin and gonadal hormones secretion, so GnRHa is often used to treat estrogen-dependent diseases such as pelvic endometriosis, precocious puberty, and breast cancer 19-21. This evidence concerns the gene GNRHR and breast cancer.