Body Size, Metabolic Factors, and Risk of Endometrial Cancer in Black Women.

Total and abdominal obesity, as well as metabolic factors such as type 2 diabetes, have been associated with a higher risk of endometrial cancer in white women. It remains unclear to what extent these factors influence the risk of endometrial cancer in black women. We followed 47,557 participants from the Black Women's Health Study for incident endometrial cancer from 1995 through 2013 (n = 274). We used Cox regression models to estimate incidence rate ratios and 95% confidence intervals while accounting for potential confounders. Incidence rate ratios for body mass indices (weight (kg)/height (m)(2)) of 25.0-29.9, 30.0-34.9, 35.0-39.9, and ≥40.0 versus those <25.0 were 1.00 (95% confidence interval (CI): 0.67, 1.48), 1.49 (95% CI: 0.97, 2.30), 2.16 (95% CI: 1.34, 3.49), and 3.60 (95% CI: 2.24, 5.78), respectively (Ptrend <0.0001). A high weight-to-height ratio was also associated with a higher risk (for the highest quartile vs. the lowest, incidence rate ratio = 2.83, 95% CI: 1.77, 4.53), as was type 2 diabetes mellitus (incidence rate ratio = 1.52, 95% CI: 1.04, 2.21). Positive associations with measures of central adiposity (waist circumference, waist-to-hip ratio, and waist-to-height ratio) and hypertension were attenuated after we controlled for body mass index. Total adiposity was an independent risk factor for endometrial cancer among black women and appeared to explain most of the associations seen with other adiposity measures and metabolic factors.