Physical activity and risk of cancers of the colon and rectum: an Italian case control study

We investigated the relationships between risk of colon and rectal cancers and physical activity in both sexes at different ages by a case-control stu dy conducted between 1991 and 1996 in six Italian centres. Cases were 1225 patients (688 men, 537 women) below the age of 75 with colon cancer and the controls included 4154 patients (2073 men, 2081 women) admitted to hospita l for acute, non-neoplastic conditions. We also analysed 722 cases of recta l cancer. Compared with the lowest level of occupational physical activity at 30-39 years old the odds ratios (OR) for the highest level were 0.64 (95 % confidence interval, CI 0.44-0.93) in men and 0.49 (95% CI 0.33-0.72) in women. The inverse association in both sexes was similar at 15-19 and 50-59 years old, No association was found in either sex for leisure-time physica l activity. For both sexes the inverse relationship between occupational ph ysical activity at 30-39 years old and colon cancer risk was not significan tly heterogeneous across strata of selected covariates, and for ascending, transverse, descending and sigmoid colon. Rectal cancer risk was not associ ated with any measure of physical activity (OR = 1.32 for men and 0.88 for women for the highest level of occupational physical activity at 30-39 year s old compared with the lowest). This study confirms that occupational phys ical activity is protective against colon, but not against rectal cancer.