title: Gallstones are associated with colonic adenoma: a meta-analysis.
abstract: BACKGROUND
  Increased levels of secondary bile acids after gallstone disease and cholecystectomy are believed to increase the risk of colorectal cancer. It remains unclear whether there is a similar risk of developing adenomas. The aim of this meta-analysis was to determine the risk of developing colonic adenomas following gallstone disease or cholecystectomy.
  
  
  METHODS
  The study was based on a systematic search of PubMed, MEDLINE, EMBASE, and Current Contents (1950-2012). Selection criteria were developed to sort for studies exploring the relationship between cholelithiasis, cholecystectomy, and colonic adenoma in an adult population. A random-effects model was used to generate pooled odds ratios (OR) and 95 % confidence intervals (CI). Publication bias and heterogeneity were assessed.
  
  
  RESULTS
  Of the 1,276 studies identified, 14 were suitable for final analysis. There were 253,059 subjects in total, 42,543 of whom were diagnosed with colonic adenoma, and 28,281 of whom had gallstones or underwent cholecystectomy. There was a significant risk of developing colonic adenoma if gallstones were present (OR = 2.26; 95 % CI = 1.83-2.81). A risk was also seen with cholecystectomy (OR = 1.15; 95 % CI = 1.04-1.26), but this risk was negated when only adjusted odds were selected (OR = 1.01; 95 % CI = 0.91-1.12). No publication bias and only low levels of heterogeneity existed.
  
  
  CONCLUSIONS
  Gallstones increase the risk of colonic adenoma. No association exists with cholecystectomy.
authors.affiliation: The Whiteley-Martin Research Centre, Discipline of Surgery, The University of Sydney, Nepean Hospital, Level 5, South Block, P.O. Box 63, Penrith, NSW 2751, Australia.
authors.forename: Corinna
authors.initials: C
authors.lastname: Chiong
authors.forename: Michael R
authors.initials: MR
authors.lastname: Cox
authors.forename: Guy D
authors.initials: GD
authors.lastname: Eslick
mesh_terms: D000236:Adenoma / Q000209:etiology*; D001647:Bile Acids and Salts / Q000032:analysis; D002763:Cholecystectomy / Q000009:adverse effects*; D003110:Colonic Neoplasms / Q000209:etiology*; D003111:Colonic Polyps / Q000209:etiology; D042882:Gallstones / Q000150:complications* / Q000601:surgery; D006801:Humans
chemical_list: D001647:Bile Acids and Salts