Higher body mass index (BMI) and inactivity have been associated with a higher risk of developing endometrial cancer, but the impact on endometrial cancer survival is unclear.Methods
Among incident endometrial cancer case subjects in the National Institutes of Health–AARP Diet and Health Study, we examined associations of prediagnosis BMI (n = 1400) and physical activity (n = 875) with overall and disease-specific 5- and 10-year mortality. Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for tumor characteristics, treatment, and other risk factors. All statistical tests were two-sided.Results
Compared with women with a BMI in the range of 18.5 to less than 25kg/m2, the hazard ratios for 5-year all-cause mortality were 1.74 (95% CI = 1.13 to 2.66) for BMI in the range of 25 to less than 30kg/m2, 1.84 (95% CI = 1.17 to 2.88) for BMI in the range of 30 to less than 35kg/m2, and 2.35 (95% CI = 1.48 to 3.73) for BMI greater than or equal to 35kg/m2 (Ptrend < .001). Higher BMI was also statistically significantly associated with poorer endometrial cancer–specific but not cardiovascular disease 5-year mortality. Hazard ratio estimates for 10-year all-cause and endometrial cancer–specific mortality as related to BMI were similar to 5-year hazard ratio estimates, whereas 10-year cardiovascular disease mortality became statistically significant (HR = 4.08; 95% CI = 1.56 to 10.71 comparing extreme BMI groups). More physical activity was related to lower all-cause 5-year mortality (HR = 0.57, 95% CI = 0.33 to 0.98 for >7 hours/week vs never/rarely), but the association was attenuated after adjustment for BMI (HR = 0.64, 95% CI = 0.37 to 1.12). No association was observed between physical activity and disease-specific mortality.Conclusions
Our findings suggest that higher prediagnosis BMI increases risk of overall and disease-specific mortality among women diagnosed with endometrial cancer, whereas physical activity lowers risk. Intervention studies of the effect of these modifiable lifestyle factors on mortality are needed.