Effect of adiposity and fat distribution on endometrial cancer risk in Shanghai women

The authors conducted a population-based case-control study of 832 endometrial cancer cases and 846 frequency-matched controls in Shanghai, China (1997-2001), to examine the association of overall adiposity and body fat distribution with disease risk. Overall adiposity was estimated using weight and body mass index (BMI); upper body fat distribution was evaluated using waist circumference and waist:hip ratio. Overall and upper-body obesity were both associated with an elevated risk of endometrial cancer. Adjusted odds ratios and 95% confidence intervals for highest-versus-lowest quartile comparisons were 2.6 (95% confidence interval (CI): 2.0, 3.5) for weight, 2.9 (95% CI: 2.2, 3.9) for BMI, 4.7 (95% CI: 3.4, 6.4) for waist circumference, and 3.5 (95% CI: 2.6, 4.8) for waist:hip ratio. The positive associations with weight and BMI vanished after results were controlled for waist circumference, while associations with waist circumference and waist:hip ratio persisted after adjustment for BMI. The positive association with upper-body obesity was more pronounced among younger women, women who had never used oral contraceptives, and women with a history of diabetes mellitus (p for multiplicative interaction < 0.05). Upper-body obesity was related to increased risk among women with low BMI. These results suggest that obesity, particularly upper-body fat deposition, is associated with an increased risk of endometrial cancer.