Estrogen regimen of women with endometrial carcinoma. A retrospective case-control study at Radiumhemmet.

In order to detect a possible association between exogeneous estrogens and endometrial cancer under Swedish circumstances, the previous use of estrogens among 622 cases of endometrial cancer 1974-77 has been compared with that of the average female population, represented by a randomly selected sample of 1 866 contemporaries to the cancer cases. Among women aged 50-69 years, 6-36 months of use of 'natural' and/or to a much lesser extent 'synthetic' estrogens was equally common in the two groups. However, starting in 1976, 3-6 years of use became increasingly more common among cancer cases. Taking 1974-77 together, cancer cases had been on such a long-term regimen more than 5 times as commonly as controls. Additional progestagen treatment was equally rare in the two groups. Tumors of estrogen users were of a significantly lower grade than those of non-users of the same age. While it cannot be concluded at this stage that estrogens are cocarcinogenic, the evident possibility motivates a somewhat cautious, restrictive approach to prescription. Progestagens could be added sequentially, though it is not yet verified that they abolish the association between endometrial cancer and estrogens that is now recognized by many investigators.