Anthropometric risk factors for colorectal polyps in African-American women

Objective: Colorectal adenomas are thought to be precursor lesions to colorectal cancer, a leading cause of cancer incidence and mortality in African-American women. Studies suggest that obesity is associated with risk of adenomas in white women, but little is known about the relation in African-American women. We prospectively examined the association between selected anthropometric factors and colorectal polyps in African-American women. Methods and Procedures: Data were obtained from the Black Women's Health Study ( BWHS), a prospective cohort study of African-American women. From 1997 to 2003, we followed 33,403 women aged >= 30 years with no prior diagnosis of cancer or polyps. Cox regression was used to estimate incidence rate ratios ( IRRs) and 95% confidence intervals ( CIs) for risk of polyps, with adjustment for potential confounders. Results: After 211,797 person-years of follow-up, 1,189 cases of colorectal polyps were reported. The IRR comparing women with a current BMI >= 35 to < 25 kg/m(2) was 1.35 ( 95% CI = 1.12-1.62), after adjustment for covariates including waist-to-hip ratio ( WHR). Women who gained >= 30 kg since age 18 were 1.76 times as likely as those who gained < 5 kg to report polyps ( 95% CI = 1.33-2.33). The IRR comparing the highest (>= 0.87) to lowest (< 0.71) quintiles of WHR was 1.26 ( 95% CI = 1.04-1.54), after adjustment for covariates including BMI. BMI at age 18, adult height, and waist circumference ( BMI-adjusted) were not materially associated with risk. Results were similar among women with a recent endoscopy. Discussion: Weight gain and obesity in adulthood may increase the risk of colorectal polyps in African-American women.