Association of estrone with the development of endometrial carcinoma

Although few clinicians suspect estrogen as the prime cause of endometrial carcinoma, a retrospective study showed the following among postmenopausal women: 70 per cent of those with endometrial carcinoma and only 23 per cent of matched control subjects used estrogen systemically. Endometrial cancer developed an average of five years earlier in those taking than in those not receiving estrogen. Forty-two per cent of those with endometrial cancer had received estrogen three years or more. Most significantly, conjugated estrogens were used by 89 per cent of postmenopausal cancer patients who had received any estrogenic substance. The increased risk of endometrial cancer for all patients receiving conjugated estrogen (the risk ratio) was 7.4. This risk ratio increased with duration of conjugated estrogen exposure, from 4.6 in patients with less than three years' exposure to 9.2 in patients with three or more years' exposure.