Purpose: Endometrial cancer (EC) survivors are the second largest group of female cancer survivors in the USA, with high prevalence of obesity and physical inactivity. While higher pre-diagnosis body mass index (BMI) has been associated with higher all-cause and disease-specific mortality, pre-diagnosis physical activity has shown mixed evidence of an association with mortality. However, the association between BMI, physical activity, and TV viewing measured after diagnosis and mortality risk among EC survivors is unknown.
Methods: We identified 580 women with EC in the NIH-AARP Diet and Health Study who completed a post-diagnosis questionnaire on BMI, leisure time moderate- to vigorous-intensity physical activity (MVPA), and TV viewing. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality.
Results: With a median follow-up time of 7.1 years, we observed 91 total deaths. We found a positive association between BMI ([Formula: see text] = 2.14, 95% CI 1.08-4.24 and mortality, and no statistically significant association between TV viewing (HR5+ vs. <3 h/day = 1.46, 95% CI 0.86-2.46) and mortality nor MVPA with mortality (HR15+ vs. 0 MET h/week = 0.72, 95% CI 0.43-1.21) after adjusting for tumor characteristics and demographic factors. Further adjustment for lifestyle and health status attenuated BMI associations ([Formula: see text] = 1.47, 95% CI 0.71-3.07), but strengthened the association between TV viewing and mortality (HR5+ vs. <3 h/day = 2.28, 95% CI 1.05-4.95).
Conclusions: Our results suggest that higher post-diagnosis BMI and TV viewing may be associated with higher mortality risk among EC patients, but that there may be complicated interrelationships between lifestyle factors of BMI, PA, and TV viewing and the mediating role of health status that need to be clarified.
Keywords: Body mass index; Cancer survivorship; Endometrial cancer; Mortality; Physical activity; Television.