title: Meta analysis of risk factors for colorectal cancer.
abstract: OBJECTIVE
  To study the risk factors for colorectal cancer in China.
  
  
  METHODS
  A meta-analysis of the risk factors of colorectal cancer was conducted for 14 case-control studies, and reviewed 14 reports within 13 years which included 5034 cases and 5205 controls. Dersimonian and Laird random effective models were used to process the results.
  
  
  RESULTS
  Meta analysis of the 14 studies demonstrated that proper physical activities and dietary fibers were protective factors (pooled OR<0.8), while fecal mucohemorrhage, chronic diarrhea and polyposis were highly associated with colorectal cancer (all pooled OR>4). The stratified results showed that different OR values of some factors were due to geographic factors or different resources.
  
  
  CONCLUSIONS
  Risks of colorectal cancer are significantly associated with the histories of intestinal diseases or relative symptoms, high lipid diet, emotional trauma and family history of cancers. The suitable physical activities and dietary fibers are protective factors.
authors.affiliation: Department of Epidemiology, School of Medicine, Zhejiang University, Hangzhou 310031, Zhejiang Province, China. ck@zjuem.zju.edu.cn
authors.forename: Kun
authors.initials: K
authors.lastname: Chen
authors.forename: Jiong-Liang
authors.initials: JL
authors.lastname: Qiu
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yu-Wan
authors.initials: YW
authors.lastname: Zhao
mesh_terms: D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D006801:Humans; D012307:Risk Factors