1. ¹Department of Surgery, Washington University School of Medicine, St Louis, MO, USA
2. ²Division of Preventive Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
3. ³Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA

Correspondence: Dr KY Wolin, Department of Surgery, Washington University School of Medicine, 660 S. Euclid Avenue, Box 8100, St Louis, MO 63110, USA; E-mail: wolink@wustl.edu

Received 2 October 2008; Revised 6 January 2009; Accepted 11 January 2009; Published online 10 February 2009.

Abstract

Although an inverse association between physical activity and risk of colon cancer is well established, a formal estimate of the magnitude of this risk reduction that includes recent studies is not available. This analysis examines the association by sex and study design, restricting analyses to studies where data for colon cancer alone were available. The authors reviewed published studies through June 2008 examining the association between physical activity and risk of colon cancer. Heterogeneity and publication bias were evaluated and random effects models used to estimate relative risks (RR). Differences by sex and study design were evaluated. A total of 52 studies were included. An inverse association between physical activity and colon cancer was found with an overall relative risk (RR) of 0.76 (95% confidence interval (CI): 0.72, 0.81). For men, the RR was 0.76 (95% CI: 0.71, 0.82); for women, this was little different, (RR=0.79, 95% CI: 0.71, 0.88). The findings from case–control studies were stronger (RR=0.69, 95% CI: 0.65, 0.74) than for cohort studies (RR=0.83, 95% CI: 0.78, 0.88). This study confirms previous studies reporting an inverse association between physical activity and colon cancer in both men and women, and provides quantitative estimates of the inverse association.