Physical activity, sedentary behaviour and colorectal cancer risk in the UK Biobank

Previous studies have shown that decreased physical activity and increased sedentary behaviours are associated with colorectal cancer risk, however it has not been shown if this is consistent across anatomical sub-sites. These associations were investigated using information from the 430,584 men and women enrolled in the UK Biobank. A total of 2391 colorectal cancer cases were recorded after a median follow-up time of 5.6 years. Physical activity was measured using metabolic equivalents (METs)-hours per week and sedentary behaviour was calculated by the amount of time spent watching television and time spent using computers. High (>60-MET-hours per week) vs low (<10-MET-hours per week) total physical activity was association with a lower colon-cancer risk, and this relationship was most apparent among men. Comparable relationships were found for proximal and distal colon tumors, but there was no association for rectal cancer. Higher levels of time watching television was associated with a higher colon cancer risk, but time spent using computers was not associated with colorectal cancer risk. These findings contribute to a large body of evidence which supports uptake of physical activity as a population-based cancer prevention program.

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