OBESITY AND ADENOMATOUS POLYPS OF THE SIGMOID COLON

The relation between obesity and adenomatous polyps of the sigmoid col on was investigated in male self-defense officials who received a reti rement health examination at three hospitals of the Self-Defense Force s in Japan between January 1991 and December 1992. Body mass index (BM I) and waist hip circumference ratio (WHR) were used as indices of obe sity. A total of 228 adenoma cases and 1484 controls with normal sigmo idoscopy were identified in 2228 men: cases having small adenomas (<5 mm in diameter) and those with large adenomas (5 mm or greater) number ed 115 and 102, respectively. Smoking, alcohol use, physical activity, rank, and hospital were controlled for by multiple logistic regressio n analysis. BMI and WHR were classified into four levels using the 30t h, 60th, and 90th percentiles of each distribution in the control as c ut off points. There was a significant two-fold elevation in the overa ll adenoma risk among men at the highest BMI level (greater than or eq ual to 26.95) compared with those at the lowest level (<22.48), but th e risk did not linearly increase: a similar increase was also noted fo r large adenomas, While WHR was only weakly related to the overall ade noma risk, the risk of large adenomas progressively increased with inc reasing levels of WHR: odds ratio (OR) 2.9 (95% confidence interval (C I) 1.4-5.9) for the highest (greater than or equal to 0.958) versus lo west (<0.878) levels. BR;II was not materially associated with adenoma risk after additional adjustment for WHR, but a positive association between WHR and large adenomas was independent of BR-II: OR 3.4 (95%CI 1,5-7.6) for the highest versus lowest levels. These findings suggest that obesity is associated with an increased risk of colon adenomas, probably with adenoma growth.