Body fat and risk of colorectal cancer among postmenopausal women.

Studies of the relationship between anthropometric indices of obesity and colorectal cancer risk in women have shown only weak and inconsistent associations. Given the limitations of such indices, we used dual-energy X-ray absorptiometry (DXA)-derived measures of body fat obtained in the Women's Health Initiative to examine the association between body fat and risk of incident colorectal cancer. We compared these risk estimates with those obtained using conventional anthropometric measurements (body mass index and waist circumference). After exclusions, the study population consisted of 11,124 postmenopausal women with DXA measurements at baseline and no history of colorectal cancer. After a median follow-up period of 12.9 years, 169 incident colorectal cancer cases were ascertained. Cox's proportional hazards models were used to estimate hazard ratios and 95 % confidence intervals for the exposures of interest. Neither DXA-derived body fat measures nor anthropometric measures showed significant associations with risk. In view of the limited number of cases, we cannot rule out the existence of weak associations of these measures with risk of colorectal cancer.