Endometrial Cancer Risk Among Younger, Overweight Women

OBJECTIVE: To examine the risk for endometrial cancer among overweight women using the World Health Organization's clinical definitions of obesity based on body mass index (BMI). METHODS: Conducted in the early 1980s, the Cancer and Steroid Hormone study was a multicenter, population-based, case-control study of breast, ovarian, and endometrial cancers among women aged 20-54 years. Participants for the case group (n=421) were identified through cancer registries and had histologically con firmed endometrial cancer. Participants for the control group (n=3,159) were chosen by random-digit dialing methods in the same regions as those in the case group. Those in the case and control groups responded to the same questions during in-person interviews. Unconditional logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The relationship between endometrial cancer and BMI (calculated as weight [kg]/[height (m)](2)) was modified by age at last menstrual period (LMP). Of women who were younger than 45 years at LMP, those with BMIs of at least 35.0 had a greater risk of endometrial cancer (56%, 30/54) than did those with normal BMIs (4%, 59/1,492, adjusted OR 21.7, 95% CI 11.3-41.7). Of women age 45 or older at LMP, those with BMIs of at least 35.0 also had a greater risk (40%, 24/60) than did those with normal BMIs (14%,168/1,235, adjusted OR 3.7,95% CI 2.0-6.6). Women younger than 45 years at LMP and those with BMIs of at least 25.0 at 18 years and as adults (25%, 31/123) had an approximately sixfold increased risk (adjusted OR 5.8, 95% CI 3.4-9.8) compared with those with normal BMIs at 18 and as adults (4%, 58/1,460). CONCLUSION: Very obese women aged 20-54 years have an elevated endometrial cancer risk, which appears heightened by early menopause. (Obstet Gynecol 2009;114:22-7)