title: Effects of Physical Activity on Risk of Colorectal Cancer: A Case-control Study.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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%.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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).
authors.affiliation: Department of Community Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Parastoo
authors.initials: P
authors.lastname: Golshiri
authors.affiliation: Department of Community Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Rasooli
authors.affiliation: Department of Gastroenterology, School of Medicine, Isfahan University of Medical Sciences and Pour-Sina-Hakim Research Center, Isfahan, Iran.
authors.forename: Mohammadhasan
authors.initials: M
authors.lastname: Emami
authors.affiliation: Department of Health Education and Health Promotion, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Arash
authors.initials: A
authors.lastname: Najimi
keywords: Case–control study; colorectal cancer; physical activity