Effects of Physical Activity on Risk of Colorectal Cancer: A Case-control Study

The prevalence of colorectal cancer (CRC) is rapidly increasing in Iran. It holds the most prevalent cancer after skin, breast, and gastric cancers among the Iranian population. The current study was designed to investigate the effects of leisure time, occupational and household physical activity as well as exercise on the risk of CRC in the Iranian population.

In this population-based case-control study, 100 individuals with a recent diagnosis of CRC who were eligible for the study were recruited between 2006 and 2008. The control groups were selected from patients' companions (excluding first- and second-degree relatives) without past history of cancer or any physical disability. Physical activity of the participants was evaluated using a Kriska retrospective physical activity questionnaire. The relation between CRC and physical activity was assessed via logistic regression model and calculating the odds ratio (OR) as well as a confidence interval (CI) of 95%.

According to the findings, the adjusted OR of occupational (OR = 0.98, 95%, CI: 0.95-1.02) and house holding physical activities (OR = 1.03, 95% CI: 0.99-1.08) were not significantly different between the case and control groups for women (P > 0.05). The risk of CRC shows a significant reduction in individuals with moderate leisure physical activities compared to those with minimal activities (OR = 0.82, CI 95%: 0.73-0.98).

The study suggests that the risk of CRC will decrease in individuals with higher leisure physical activities (especially with an increase in hours of brisk walking during the day).