Study objective: To assess the incidence of endometrial cancer in 509 women who had undergone hysteroscopic endometrial ablation in two centers between 1978 and 1994. All patients had normal endometrial histology before ablation.
Design: Retrospective cohort study (Canadian Task Force classification II-2).
Setting: Teaching hospital-affiliated private practices.
Patients: Five hundred nine women with perimenopausal bleeding.
Intervention: The patients were contacted directly, by mail or phone, and asked if they had had a diagnosis or treatment for cancer or precancer of the endometrium. The list of unreachable patients was submitted to the National Death Index. After this, names and other pertinent data of the remaining patients were submitted to the Cancer Registries of the 50 states and Washington, DC. Forty-two patients were omitted from these searches due to insufficient information or because they were unreachable, and one excluded because of a diagnosis of Bloom's syndrome. The comparative incidence was obtained from the U.S. SEER data of age-specific rates of endometrial cancer published by the National Cancer Institute.
Measurements and main results: Fifty-one percent of the patients were contacted directly yielding one case of endometrial cancer. Eight patients had died, but none from endometrial cancer. One patient was located in the New Jersey Cancer Registry. A total of 5063 woman-years was identified with two cases of endometrial cancer. The expected incidence was 1.66 cases in an age-matched group with known length of follow-up from the U.S. SEER data. There is no significant difference between the two groups.
Conclusion: The flaws in the databases include the lack of data on subsequent hysterectomy for benign disease in both the treated group and the SEER database. Low risk for endometrial cancer is narrowly defined to normal endometrium preablation. Nevertheless, the data give an approximation of the incidence for endometrial cancer, and should serve as a benchmark for prospective studies in patients undergoing endometrial ablation as well as a resource to counsel patients in the choice between ablation and hysterectomy.