Progesterone, progestins and the endometrium in perimenopause and in menopausal hormone therapy.

ABSTRACT

It is well established that unopposed estrogen for hormone therapy in postmenopausal women (MHT) induces a dose-related stimulation of the endometrium associated with an increased risk of hyperplasia and endometrial cancer. Progesterone acts physiologically to counteract the proliferative effects of estradiol during the menstrual cycle. In MHT, progestogens protect the endometrium against the proliferative effects of estrogens in women with a uterus. Recent data suggest that, whereas micronized progesterone is apparently safer for the breast, it could be less efficient than synthetic progestin on the endometrium. An update on progestogen and endometrial safety in MHT is the subject of this review.