Domain-specific physical activity and the risk of colorectal cancer: results from the Melbourne Collaborative Cohort...

Physical activity reduces the risk of colorectal cancer (CRC), but the relevant evidence derives primarily from self-reported recreational and occupational activity. Less is known about the contribution of other domains of physical activity, such as transport and household. We examined associations between domain-specific physical activities and CRC risk within the Melbourne Collaborative Cohort Study.

Analyses included 23,586 participants who were free from invasive colorectal cancer and had completed the International Physical Activity Questionnaire-Long Form at follow-up 2 (2003-2007). Cox regression, with age as the time metric, was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for ordinal categories of each physical activity domain.

Adjusted HRs for the highest versus the lowest categories of physical activity were 0.71 (95% CI: 0.51-0.98; p_trend = 0.03) for recreational activity; 0.80 (95% CI: 0.49-1.28; p_trend = 0.38) for occupational activity; 0.90 (95% CI: 0.68-1.19; p_trend = 0.20) for transport activity; and 1.07 (95% CI: 0.82-1.40; p_trend = 0.46) for household activity.

Recreational activity was associated with reduced CRC risk. A non-significant, inverse association was observed for occupational activity, whereas no association was found for transport or household domains.