title: Meta-analysis of different test indicators: Helicobacter pylori infection and the risk of colorectal cancer.
abstract: OBJECTIVE
  Recent studies have demonstrated the relationship between Helicobacter pylori infection and the risk of colorectal carcinoma. However, the results of these studies remain controversial as the studies were relatively small in size and partially differed in designs, and so we reviewed the published studies and carried out a meta-analysis to further explore this relationship.
  
  
  METHODS
  We performed an extensive systematic review to find all the published case-control studies up to Jan. 2007 using electronic searching, hand searching, and reference lists of retrieved articles. Odds ratio (OR) was employed to evaluate the relationship of H. pylori infection and risk of colorectal cancer. Summary estimates were obtained using random effect models according to the result of a statistical test for heterogeneity across the studies. The presence of possible publication bias was assessed using different statistical approaches.
  
  
  RESULTS
  Thirteen studies were included, and summary OR 1.49 (95% confidence interval [CI] 1.17-1.91) was estimated for the association between H. pylori infection and colorectal cancer. Summary OR 1.56 (95% CI 1.14-2.14) was estimated for the association between immunoglobulin G antibody and colorectal cancer risk. By trimming and filling, the number of inputted studies was zero, and summary OR was still 1.49 (95% CI 1.17-1.91). The graphical funnel plot appeared asymmetrical, but there was no statistical evidence of publication bias. The method of fail-safe suggested that the effect of publication bias was small.
  
  
  CONCLUSIONS
  Current evidence, though limited, suggests that there is a possible increase in risk of colorectal cancer because of H. pylori infection.
authors.affiliation: Department of Epidemiology, School of Public Health, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China. zhao_yashuang@263.net
authors.forename: Ya-Shuang
authors.initials: YS
authors.lastname: Zhao
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Chang
authors.forename: Bing
authors.initials: B
authors.lastname: Han
authors.forename: Ding-Yun
authors.initials: DY
authors.lastname: You
mesh_terms: D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology*; D014943:Global Health; D016481:Helicobacter Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016017:Odds Ratio; D012307:Risk Factors