title: Cholecystectomy as a risk factor for colorectal cancer: a meta-analysis.
abstract: BACKGROUND
  It has been suggested that there is an increased risk of colorectal cancer after cholecystectomy due to increased levels of secondary bile acids. Some studies suggest the risk is higher for women and for the development of right-sided tumours.
  
  
  METHODS
  A review of the literature yielded 95 relevant studies, of which 35 were suitable for a meta-analysis involving age- and sex-matched controls.
  
  
  RESULTS
  The pooled odds ratio for a positive association between cholecystectomy and colorectal cancer was 1.11 (95% confidence interval (CI), 1.02 to 1.21). For women the odds ratio was 1.14 (95 % CI, 10.01 to 1.28) and for right-sided cancer 1.86 (95% CI, 1.31 to 2.65).
  
  
  CONCLUSIONS
  It is possible that this small observed association may be due to a publication bias for positive results or bias within the included studies. If it is indeed a real effect, the risk to an individual is very small.
authors.affiliation: Dept. of Public Health and Epidemiology, King's College School of Medicine and Dentistry, London, UK.
authors.forename: F D
authors.initials: FD
authors.lastname: Reid
authors.forename: P M
authors.initials: PM
authors.lastname: Mercer
authors.forename: M
authors.initials: M
authors.lastname: harrison
authors.forename: T
authors.initials: T
authors.lastname: Bates
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001647:Bile Acids and Salts / Q000502:physiology; D002763:Cholecystectomy; D015179:Colorectal Neoplasms / Q000209:etiology* / Q000503:physiopathology; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011183:Postoperative Complications / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D001647:Bile Acids and Salts