Mahmood S, et al. – This study analyzed the evidence on the link between domain–specific physical activity or sedentary behaviour and the risk of colon and/or rectal cancer. Overall, promoting physical activity and attenuating sedentary behaviour may be beneficial in the prevention of colorectal cancer.

Methods

• Researchers searched Medline, Embase and Web of Science from inception to December 2015 for studies assessing domain-specific physical activity or sedentary behaviour and the risk of colon and/or rectal cancer.
• They extracted maximally adjusted relative risks (RRs) except when RRs not adjusted for body mass index, were also presented.
• They also used random-effects meta-analysis to compute pooled RRs comparing the highest versus the lowest level of exposure.
• In addition, meta-regression was used to assess sources of heterogeneity in estimates.

Results

• Researchers identified 17 cohort and 21 case-control studies, of which 17 had occupational data, 23 had recreational data, three each had data on transport and household physical activity domains, and 6 studies had data on occupational sedentary behaviour.
• Findings demonstrated that the pooled relative risks (RRs) for colon cancer were 0.74 (95% confidence interval (CI): 0.67, 0.82) for occupational activity, 0.80 (95% CI: 0.71, 0.89) for recreational activity, 0.66 (95% CI: 0.45, 0.98) for transport-related physical activity, 0.85 (95% CI: 0.71, 1.02) for household physical activity, and 1.44 (95% CI: 1.28, 1.62) for occupational sedentary behaviour.
• Data reported that, for rectal cancer, the pooled RRs were 0.88 (95% CI: 0.79, 0.98) for occupational activity, 0.87 (95% CI: 0.75, 1.01) for recreational activity, 0.88 (95% CI: 0.70, 1.12) for transport-related physical activity, 1.01 (95% CI: 0.80, 1.27) for household physical activity, and 1.02 (95% CI: 0.82, 1.28) for occupational sedentary behaviour.