Body mass index trumps age in decision for endometrial biopsy: cohort study of symptomatic premenopausal women

BACKGROUND: Clinical guidelines recommend that women with abnormal uterine bleeding with risk factors have an endometrial biopsy to exclude hyperplasia or cancer. Given the majority of endometrial cancer occurs in postmenopausal women, it has not been widely recognized that obesity is a significant risk factor for endometrial hyperplasia and cancer in young, symptomatic, premenopausal women. OBJECTIVE: We sought to evaluate the effect of body mass index on risk of endometrial hyperplasia or cancer in premenopausal women with abnormal uterine bleeding. STUDY DESIGN: This was a retrospective cohort study in a single large urban secondary women's health service. Participants were 916 premenopausal women referred for abnormal uterine bleeding of any cause and had an endometrial biopsy from 2008 through 2014. The primary outcome was complex endometrial hyperplasia (with or without atypia) or endometrial cancer. RESULTS: Almost 5% of participants had complex endometrial hyperplasia or cancer. After adjusting for clinical and demographic factors, women with a measured body mass index >= 30 kg/m(2) were 4 times more likely to develop complex hyperplasia or cancer (95% confidence interval, 1.36-11.74). Other risk factors were nulliparity (adjusted odds ratio, 3.08; 95% confidence interval, 1.43-6.64) and anemia (adjusted odds ratio, 2.23; 95% confidence interval, 1.14-4.35). Age, diabetes, and menstrual history were not significant. CONCLUSION: Obesity is an important risk factor for complex endometrial hyperplasia or cancer in premenopausal women with abnormal uterine bleeding who had an endometrial biopsy in a secondary gynecology service. As over half of women with the outcome in this study were age<45 years, deciding to biopsy primarily based on age, as currently recommended in national guidelines, potentially misses many cases or delays diagnosis. Body mass index should be the first stratification in the decision to perform endometrial biopsy and/or to refer secondary gynecology services.