title: Inflammatory bowel disease and risk of cholangiocarcinoma: evidence from a meta-analysis of population-based studies.
abstract: OBJECTIVE
  Patients with inflammatory bowel disease (IBD) have an increased risk of extra-intestinal cancer, whereas its impact on cholangiocarcinoma (CC) remains unknown. The aim of this study was to obtain a reliable estimate of the risk of CC in IBD patients through a meta-analysis of clinical observational studies.
  
  
  METHODS
  Relevant studies were retrieved by searching PUBMED, EMBASE and Web of Science Databases up to Dec 2013. Four population-based case-control and two cohort studies with IBD were identified. Summary relative risk (RR) and its corresponding 95% confidence interval (CI) were calculated using a random-effects model. Potential sources of heterogeneity were detected using subgroup analyses.
  
  
  RESULTS
  The pooled risk estimate indicated IBD patients were at increased risk of CC (RR = 2.63, 95%CI = 1.47-4.72). Moreover, the increased risk of CC was also associated with Crohn's disease (RR = 2.69, 95%CI = 1.59-4.55) and ulcerative colitis (RR = 3.40, 95%CI = 2.50-4.62). In addition, site-specific analyses revealed that IBD patients had an increased risk of intrahepatic CC (ICC) (RR = 2.61, 95%CI = 1.72-3.95) and extrahepatic CC (ECC) (RR = 1.47, 95%CI = 1.10- 1.97).
  
  
  CONCLUSIONS
  This study suggests the risk of CC is significantly increased among IBD patients, especially in ICC cases. Further studies are warranted to enable definite conclusions to be drawn.
authors.affiliation: Department of Critical Care Medicine, Jinhua Municipal Central Hospital, Jinhua Hospital of Zhejiang University, Jinhua, China E-mail : yexiaohuare@qq.com.
authors.forename: Jia-Ping
authors.initials: JP
authors.lastname: Huai
authors.forename: Jin
authors.initials: J
authors.lastname: Ding
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Ye
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Chen
mesh_terms: D001650:Bile Duct Neoplasms / Q000453:epidemiology*; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000453:epidemiology*; D003093:Colitis, Ulcerative / Q000453:epidemiology*; D003424:Crohn Disease / Q000453:epidemiology*; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology; D012307:Risk Factors