The aim of this retrospective study was to quantify the relationship of uterine cancer with body mass index (BMI) in a cohort of US women undergoing hysterectomy. The authors used the University Health System Consortium database to identify all women who underwent total hysterectomy between 2008 and 2012 with a recorded BMI of 25 to 40 kg/m2. A total of 165,876 women were identified. Least squares regression analysis was used to assess the association between increasing BMI and the proportion of women with a diagnosis of uterine cancer. Adjustment for other known risk factors (including age, race, and other comorbidities) was performed using multivariate binary logistic regression.
Among the 165,876 women who underwent hysterectomy during the study period, 6905 (4.2%) had a recorded BMI and met other inclusion criteria; 1891of these (27.4% [429/6905]) had uterine cancer. Least squares fit showed a linear relationship for the probability of uterine malignancy versus BMI; the association was described by the equation: y = 0.015x − 0.23, R 2 = 0.92, where risk of uterine cancer is the ordinate, and BMI is the abscissa. Multivariate analysis with adjustment for age and race showed that each 1-U increase in BMI was independently associated with an 11% increase in the proportion of patients diagnosed with uterine cancer among women with a BMI of 25 to 40 kg/m2; the odds ratio was 1.11, with a 95% confidence interval of 1.09 to 1.13; P < 0.001.
These data show that the probability of uterine malignancy increases linearly with an increase in BMI among a population of overweight and obese women undergoing hysterectomy. Even modest weight gain appears to significantly raise the risk of cancer. The results have important implications with respect to risk prediction and counseling for women with a BMI of 25 to 40 kg/m2, which includes more than half of all US women.
Division of Gynecologic Oncology, Department of Reproductive Medicine, Rebecca and John Moores UCSD Cancer Center, La Jolla, CA (K.K.W., N.R.S., M.-A.D., C.C.S., M.T.M., and S.C.P.); and the Center for Health Promotion and Prevention Research, The University of Texas School of Public Health, Houston, TX (A.M.R.)