Exogenous estrogen and endometrial carcinoma: Case-control and incidence study

Abstract Recent independent case-control studies have indicated that treatment with exogenous estrogen is associated with an increase in the risk of endometrial cancer. This question was studied in Olmsted County, Minnesota, by identifying all cases of endometrial cancer among residents over a 30 year period (1945 through 1974) and by matching four controls to each of the 145 patients. The rate of past exposure to any exogenous estrogen for any duration was about the same for patients as for controls. However, the estimated relative risk of endometrial cancer associated with conjugated estrogen treatment of 6 months or longer was 4.9 (P