title: Helicobacter pylori infection and normal colorectal mucosa-adenomatous polyp-adenocarcinoma sequence: a meta-analysis of 27 case-control studies.
abstract: OBJECTIVE
  The study aimed to determine whether Helicobacter pylori infection is associated with colorectal adenocarcinoma and to quantify the extent of the risk.
  
  
  METHODS
  A literature search was performed to identify studies published between 1995 and 2012 for relevant risk estimates. Fixed and random effect meta-analytical techniques were conducted for colorectal adenocarcinoma and adenomatous polyp.
  
  
  RESULTS
  Twenty-seven case-controlled studies involving 3450 adenocarcinoma patients, 1304 adenomatous polyp patients and more than 4000 controls were included. Helicobacter pylori was associated with an increased risk of colorectal adenocarcinoma and adenomatous polyp [odds ratio (OR) 1.24, 95% CI 1.12-1.37, P = 0.66; OR 1.87, 95% CI 1.53-2.28, P = 0.81]. There was a significant association between the CagA-positive strain and adenocarcinoma risk (OR 1.22, 95% CI 1.08-1.37, P = 0.05). In addition, there was an increased risk of tubular adenoma and villous adenoma formation (OR 3.06, 95% CI 1.98-4.73, P = 0.14; OR 2.05, 95% CI 0.84-4.97, P = 0.86).
  
  
  CONCLUSIONS
  The meta-analysis suggests a promoting effect of Helicobacter pylori on the risk of adenocarcinoma. It also suggests that Helicobacter infection might have its influence at the start of the adenomatous polyp disease sequence.
authors.affiliation: Department of Internal Medicine, Tianjin Union Medicine Center & Tianjin People's Hospital, Tianjin, China.
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: M Y
authors.initials: MY
authors.lastname: Sun
authors.forename: S L
authors.initials: SL
authors.lastname: Shi
authors.forename: Z S
authors.initials: ZS
authors.lastname: Lv
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D018256:Adenomatous Polyps / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D016481:Helicobacter Infections / Q000473:pathology*; D016480:Helicobacter pylori; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology; D008297:Male; D016017:Odds Ratio; D012307:Risk Factors
keywords: Colorectal neoplasms; adenomatous polyps; bacteria; helicobacter pylori; meta-analysis