Background Few studies have examined the associations between physical activity (PA), sedentary behaviour (SB) and risk of colorectal neoplasia (CN).
Methods We systematically searched Medline, Embase, PsyInfo, Cochrane and other sources from their inception to 30 September 2018 for cohort, case-control and cross-sectional studies that evaluated these associations in asymptomatic, average-risk subjects. Random-effect models were used to estimate relative risks (RRs) of any-type CN, advanced CN, and non-advanced CN, respectively, in individuals with the highest versus the lowest level of PA and SB. Dose-response analyses and subgroup analyses were conducted. The I2 statistic was used to examine heterogeneity among studies.
Results We identified 32 observational studies, including 17 cross-sectional studies, 10 case-control studies and five longitudinal studies. PA (highest vs lowest) was inversely associated with risk for any-type CN (n=23 studies) and advanced CN (n=15 studies), with a RR of 0.77 (95% CI=0.71 to 0.83, I2=57.5%) and 0.73 (95% CI=0.63 to 0.82, I2=45.5%), respectively. There was no association between PA and non-advanced CN (n=5 studies). There was an as association between PA and any-type CN in both sexes, and also for the distal colon. We found no dose–response relationship between PA and any-type or advanced CN. Based on three studies identified, SB time (longest vs shortest) was associated with an increased risk of advanced CN (RR=1.24, 95% CI 1.04 to 1.49, I2=14.4%). No publication bias was detected by Begg’s test.
Conclusion We report a 23% lower relative risk of any type of CN and a 27% lower risk of advanced CN in people with the highest level of PA compared with those in the lowest.
- physical activity
- sedentary behaviour
- colorectal cancer
- risk factor
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JW and LH are joint first authors.
Contributors Contributors JJW, LWH, MW and CSW conceived the design of the study. YG and YHW helped to revise the design. JJW, LWH, JJH and WJZ acquired data from selected studies. SQC, PPB, YMG and YFZ were involved in the statistical analyses. JJW and LWH drafted the manuscript. All authors were involved in the analysis and interpretation of the data; they carried out a critical revision of the manuscript for important intellectual content and also read and approved the manuscript. JJW and LWH had full access to all of the data in the study. MW and CSW are the guarantors.
Funding The Fundamental Research Funds for the China Institute of Sport Science (grant no. 18-40)
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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