Energy intake, body mass index, physical activity, and the colorectal adenoma-carcinoma sequence

Little is known about the precise relationship between energy intake, overw eight, sedentary lifestyle, and steps in the colorectal adenoma-carcinoma p athway. We studied these parameters within a case-control study. Patients w ith adenomas < 10 mm (n = 154) or > 10 min (n = 208) were compared with pol yp-free controls (n = 426) for determining factors associated with adenoma formation, i.e., observed for small and large adenomas, or with adenoma gro wth only. Colorectal cancer cases (n = 171) were compared with population c ontrols (n = 309) to determine factors specific to the final stage, cancer. Exercise reduced the risk of cancer [odds ratio (OR) = 0.3, 95% confidence interval (CI) = 0.2-0.5 for high vs. low physical activity] but had little influence on adenomas. High energy intake increased the risk of cancer [OR for 5th vs. 1st quintile (OR5) = 1.6, 95% CI = 0.9-2.9, p = 0.02], but not of adenomas. High body mass index (BMI) significantly increased the risk o f large adenomas (OR, = 2.1, 95% CI = 1.2-3.5, p = 0. 02 and OR5 = 1.7, 95% CI = 1.0-3.1, p = 0.25) for large and small adenomas vs. polyp-free contro ls. Neither height nor weight nor BMI influenced the risk of cancer. Result s were unmodified when controlling for dietary risk factors and family hist ory. Energy intake, a sedentary lifestyle, and high BMI were independently associated with a high risk of cancer use for large adenomas, which indicat es an effect on promotion of colorectal tumors. These findings suggest that preventive advice regarding these factors should be provided, even late in life, to decrease the risk of colorectal cancer.