Risk factors for developing endometrial cancer after benign endometrial sampling

Objective: To identify risk factors for endometrial cancer after benign results of endometrial biopsy or dilation and curettage (D&C). Methods: Nested case-control study from Rochester Epidemiology Project data. Among 370 Olmsted County, Minnesota, residents who received an endometrial cancer diagnosis between 1970 and 2008, we identified 90 patients (24.5%) who had previous benign endometrial biopsy or D&C results (no atypical hyperplasia). We compared them with 172 matched control group participants who had benign endometrial biopsy or D&C results without subsequent endometrial cancer. Results: Using a multivariable conditional logistic regression model, we found that oral contraceptive pill (OCP) use was protective (odds ratio [OR] 0.18, 95% CI [CI] 0.08-0.45; P<.001), and personal history of colorectal cancer (OR 4.44, 95% CI 1.02-19.31; P<.05), endometrial polyp (OR 4.12, 95% CI 1.40-12.17; P=.01), and morbid obesity (OR 3.40, 95% CI 1.18-9.78; P<.03) were independently associated with subsequent endometrial cancer. Compared with the presence of no risk factor, presence of one and two or more risk factors increased the risk of endometrial cancer by 8.12 (95% CI 3.08-21.44) and 17.87 (95% CI 5.57-57.39) times, respectively. Assuming a 2.6% lifetime risk of endometrial cancer, ORs of 8.12 and 17.87 for one and two or more of the four aforementioned risk factors confer a lifetime risk of approximately 18% and 32%, respectively. Conclusion: One fourth of patients with endometrial cancer had previous benign endometrial biopsy or D&C results. Personal history of colorectal cancer, presence of endometrial polyps, and morbid obesity are the strongest risk factors for having endometrial cancer after a benign endometrial biopsy or D&C result, and OCP use is the strongest protective factor.