title: Infections of Helicobacter spp. in the biliary system are associated with biliary tract cancer: a meta-analysis.
abstract: OBJECTIVE
  As Helicobacter spp. have been successfully isolated from the biliary system, a hypothetical question was raised about the role of these organisms in the development of biliary tract cancer. This meta-analysis has been carried out to explore the association between Helicobacter spp. infection and biliary tract cancer.
  
  
  METHODS
  A systematic literature search was carried out to identify all eligible articles. Meta-analysis used odds ratio and a random-effect model, and 95% confidence intervals for odds ratios were calculated. Heterogeneity was quantitatively assessed using the χ-test, with significance set at a P-value of 0.01, and was measured using the I-statistic.
  
  
  RESULTS
  Ten studies published between 2002 and 2011 were finally included for meta-analysis. Helicobacter pylori, Helicobacter bilis, Helicobacter hepaticus, and Helicobacter ganmani were studied. With heterogeneity (I=0%, P=0.685), a significantly higher pooled infection rate of Helicobacter spp. was observed in the biliary tract cancer group compared with the normal group (P=0.0001) and the benign biliary disease group, respectively (P=0.0001). Studies from East Asia and South Asia showed a higher prevalence of Helicobacter spp. in the malignant group. Evidence supporting the higher presence of Helicobacter spp. in the cancer group was obtained using PCR and immunohistochemical analysis of specimens from bile and biliary tissues.
  
  
  CONCLUSIONS
  Our meta-analysis suggests a trend of a higher presence of Helicobacter spp. in patients with biliary tract cancers compared with normal controls or those with benign biliary diseases.
authors.affiliation: Department of General Surgery, Xinhua Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200092, China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhou
authors.forename: Jian-dong
authors.initials: JD
authors.lastname: Wang
authors.forename: Ming-zhe
authors.initials: MZ
authors.lastname: Weng
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xue-feng
authors.initials: XF
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Gong
authors.forename: Zhi-wei
authors.initials: ZW
authors.lastname: Quan
mesh_terms: D001660:Biliary Tract Diseases / Q000453:epidemiology / Q000382:microbiology; D001661:Biliary Tract Neoplasms / Q000453:epidemiology / Q000382:microbiology*; D002769:Cholelithiasis / Q000453:epidemiology / Q000382:microbiology; D016998:Helicobacter / Q000145:classification / Q000302:isolation & purification; D016481:Helicobacter Infections / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D015995:Prevalence