title: Meta-analysis of observational studies on cholecystectomy and the risk of colorectal adenoma.
abstract: OBJECTIVE
  Cholecystectomy has been suggested as a risk factor for colorectal cancer. However, the association of cholecystectomy and the risk of colorectal adenoma (CRA) remains unclear. We conducted a meta-analysis of observational studies to explore this relationship.
  
  
  METHODS
  We identified studies by a literature search of MEDLINE and EMBASE through 30 September 2011, and by searching the reference lists of pertinent articles. Summary relative risks (SRRs) with their 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I2.
  
  
  RESULTS
  A total of 10 studies (including 4061 CRA cases) were included in this meta-analysis. Analysis of these 10 studies found that no effect of cholecystectomy on the risk of CRAs was shown (SRR, 1.17; 95% CI: 0.93-1.48), with no significant heterogeneity among these studies (P heterogeneity=0.106, I2=37.9%). This null association was seen in both men and women (men: SRR=1.00, 95% CI: 0.58-1.73; women: SRR=1.39, 95% CI: 0.95-2.04).
  
  
  CONCLUSIONS
  The results of this meta-analysis suggest that there is no positive association between previous cholecystectomy and the risk of CRA development in both men and women.
authors.affiliation: Department of Gastroenterology, First People's Hospital of Nantong, Jiangsu, China.
authors.forename: Chengjin
authors.initials: C
authors.lastname: Zhao
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Ge
authors.forename: Yamin
authors.initials: Y
authors.lastname: Wang
authors.forename: Junbo
authors.initials: J
authors.lastname: Qian
mesh_terms: D000236:Adenoma / Q000209:etiology*; D002763:Cholecystectomy / Q000009:adverse effects*; D015179:Colorectal Neoplasms / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D017594:Publication Bias; D018570:Risk Assessment / Q000379:methods