Use of the Progestogen Challenge Test to Reduce the Risk of Endometrial Cancer

In contrast to several retrospective studies reporting an increased risk of endometrial cancer during the mid-1970s, especially in estrogen-treated postmenopausal women, the number of cancers at Wilford Hall USAF Medical Center has steadily declined despite continued estrogen use. In a 4-year study from 1975 to 1978, there were 17 adenocarcinomas of the endometrium during 10,872 patient-years of observation, for an overall annual incidence of 156.4100,000 women. The highest incidence of endometrial cancer (359.1:100,000) was found in those women using estrogens alone. The lowest incidence of cancer was observed in the estrogen-progestogen users (56.4:100,000) and was significantly lower (P