title: Association of sedentary behaviour with colon and rectal cancer: a meta-analysis of observational studies.
abstract: BACKGROUND
  Sedentary behaviour is ubiquitous in modern society. Emerging studies have focused on the health consequences of sedentary behaviour, including colorectal cancer, but whether sedentary behaviour is associated with the risks of colon and rectal cancer remains unclear. No systematic reviews have applied quantitative techniques to independently compute summary risk estimates. We aimed to conduct a meta-analysis to investigate this issue.
  
  
  METHODS
  We searched PubMed, Embase, and Google Scholar databases up to May 2013 to identify cohort and case-control studies that evaluated the association between sedentary behaviour and colon or rectal cancer. A random-effect model was used to pool the results of included studies. Publication bias was assessed by using Begg's funnel plot.
  
  
  RESULTS
  Twenty-three studies with 63 reports were included in our meta-analysis. These groups included 4,324,462 participants (27,231 colon cancer cases and 13,813 rectal cancer cases). Sedentary behaviour was significantly associated with colon cancer (relative risk (RR): 1.30, 95% confidence interval (CI): 1.22-1.39) but did not have a statistically significant association with rectal cancer (RR 1.05, 95% CI, 0.98-1.13). Subgroup analyses suggested that the odds ratio (OR) of colon cancer was 1.46 (95% CI: 1.22-1.68) in the case-control studies, and the RR was 1.27 (95% CI: 1.18-1.36) in the cohort studies, the OR of rectal cancer was 1.06 (95% CI: 0.85-1.33) in the case-control studies, and the RR was 1.06 (95% CI, 1.01-1.12) in the cohort studies.
  
  
  CONCLUSIONS
  Sedentary behaviour is associated with an increased risk of colon cancer. Subgroup analyses suggest a positive association between sedentary behaviour and risk of rectal cancer in cohort studies. Reducing sedentary behaviour is potentially important for the prevention of colorectal cancer.
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Cong
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Gan
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: H L
authors.initials: HL
authors.lastname: Sun
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: J
authors.initials: J
authors.lastname: Deng
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: S Y
authors.initials: SY
authors.lastname: Cao
authors.affiliation: 1] School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China [2] Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Lu
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D039781:PubMed; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D012307:Risk Factors; D057185:Sedentary Behavior