Does Low-Potency Estrogen Carry a Risk of Endometrial Cancer?
Low-potency estrogen, such as 1 to 2 mg of estriol, is increasingly used in Europe in the belief that such formulations provide the benefits of hormone replacement therapy without the risk of endometrial hyperplasia and cancer. The risk of endometrial cancer with low-dose estrogen, however, has not been adequately studied. Weiderpass and colleagues investigated this risk in women 50 to 74 years of age who received hormone replacement therapy. The population-based, case-control study was conducted in Sweden. A total of 789 cases of newly diagnosed endometrial cancer in postmenopausal women was identified through six regional cancer registries. These cases were matched by age to 3,368 women who served as the control group. Questionnaires were mailed to obtain data on the use of hormones and other pertinent information about the reproductive and medical history. Missing information was obtained by telephone interviews. The incidence of endometrial cancer in women who had used oral or vagi
