The prevention of endometrial cancer in postmenopausal women with progestogens.

Due to adverse publicity alleging an increased risk of endometrial cancer with estrogen therapy, a prospective study was begun in 1976 to determine the incidence of this disease in postmenopausal women. During 5,025 patient-years of observation in 1976-1977, 6 adenocarcinomas of the endometrium were diagnosed for an incidence of 1.2:1,000 postmenopausal women per year. No endometrial malignancies were detected in 2,552 patient years of therapy with estrogens and progestogens. In 1,028 patient-years of observation where estrogens only was the therapy, there were 3 endometrial cancers for an incidence of 2.9:1,000. Adenocarcinoma of the endometrium was found in 2 of the untreated group, which gave an incidence of 3.0:1,000. The sixth endometrial cancer occurred in a patient using estrogen vaginal cream. During this same period, 139 perimenopausal and postmenopausal women were treated with progestogens for endometrial hyperplasia. The hyperplasia was reversed to normal endometrium in 133 patients (95.7%). Hyperplasia is a precancerous lesion and should be treated with either progestogens or hysterectomy. All postmenopausal women with a uterus should be given the Progestogen Challenge Test and the progestogen continued each month as long as bleeding follows. These methods will prevent most endometrial cancers.