Use of progestogen therapy.

Estrogen therapy for postmenopausal women has received adverse publicity since the mid-1970s because several reports implicated estrogens with an increased risk of endometrial cancer. Other studies indicated that the risk of endometrial malignancy is reduced when a progestogen is added to the estrogen. Not all postmenopausal women need estrogen replacement, since many are symptom free because they continue to produce endogenous estrogens. Within this group may be the women at greatest risk for adenocarcinoma of the endometrium. The progestogen challenge test was devised to identify women at greatest risk for endometrial cancer. The number of endometrial malignancies declined at Wilford Hall U.S. Air Force Medical Center with increasing use of this test from 1975 through 1983. The lowest incidence of endometrial cancer was observed in the estrogen-progestogen users (49.0 per 100,000) and was significantly lower than that found in either the unopposed estrogen users (390.6 per 100,000; p less than or equal to 0.0001) or in the untreated women (245.5 per 100,000; p less than or equal to 0.005). The incidence of breast cancer was also significantly lower in the estrogen-progestogen users (66.8 per 100,000) than in the untreated group (343.5 per 100,000) and lower than that expected from two national cancer surveys (188.3 and 229.2 per 100,000; p less than or equal to 0.01). Progestogens should be added to estrogen replacement therapy in women who have undergone a hysterectomy, as well as in those with an intact uterus.