Body mass index and colon cancer in a national sample of adult US men and women.

The evidence supporting obesity as a risk factor for colon cancer remains inconclusive, especially among women. The author studied the association between obesity and colon cancer in a nationally representative cohort of men and women aged 25-74 years who participated in the First National Health and Nutrition Examination Survey from 1971 to 1975 and were subsequently followed up through 1992. Among the 13,420 persons included in the analytic sample, 222 incident cases of colon cancer were identified. Height and weight were measured during the baseline examination. Compared with participants whose body mass index was less than 22 kg/m2, the hazard ratios were 1.79 (95% confidence interval (CI): 0.87, 3.71), 1.86 (95% CI: 0.86, 4.03), 2.47 (95% CI: 1.14, 5.32), 3.72 (95% CI: 1.68, 8.22), and 2.79 (95% CI: 1.22, 6.35) for participants with a body mass index of 22-<24 kg/m2, 24-<26 kg/m2, 26-<28 kg/m2, 28-<30 kg/m2, and > or = 30 kg/m2, respectively. The hazard ratios were similar for men and women. Subscapular skinfold thickness, but not triceps skinfold thickness, was positively associated with colon cancer incidence among men but not women, after adjustment for body mass index and other possible confounders. These results strongly support the hypothesis that excess body weight is a risk factor for colon cancer among both men and women.