title: Hepatitis C virus infection and the risk of intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma: evidence from a systematic review and meta-analysis of 16 case-control studies.
abstract: BACKGROUND
  Studies investigating the association between hepatitis C virus (HCV) infections and the occurrence of cholangiocarcinoma (CCA), especially intrahepatic cholangiocarcinoma (ICC), have shown inconsistent findings. Although previous meta-analyses referred to HCV and CCA, they mainly focused on ICC rather than CCA or extrahepatic cholangiocarcinoma (ECC). Since then, relevant new studies have been published on the association between HCV and ICC. Since the different anatomic locations of CCA have distinct epidemiologic features and different risk factors, it is necessary to evaluate the relationship between HCV infection and ICC, ECC, and CCA.
  
  
  METHODS
  Relevant studies were identified by searching PUBMED, EMBASE, and MEDLINE databases prior to 1 August 2013. Pooled risk estimates were calculated with random-effects models using STATA 11.0.
  
  
  RESULTS
  A total of 16 case-control studies were included in the final analysis. Pooled risk estimates showed a statistically significant increasing risk of CCA (odds ratio (OR) = 5.44, 95% CI, 2.72 to 10.89). The pooled risk estimate of ICC (OR = 3.38, 95% CI, 2.72 to 4.21) was higher than that of ECC (OR = 1.75, 95% CI, 1.00 to 3.05). In a subgroup analysis, the pooled risk estimate of ICC in studies from North America was obviously higher than in Asia (6.48 versus 2.01). The Begg funnel plot and Egger test showed no evidence of publication bias.
  
  
  CONCLUSIONS
  HCV infection is associated with the increasing risk of CCA, especially ICC.
authors.affiliation: Department of Surgery, Medical Center of Digestive Disease, Shanghai Jiao Tong University Affiliated First People's Hospital, No. 100, Haining Road, 200080, Shanghai, China. lihao6656@163.com.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Surgery, Medical Center of Digestive Disease, Shanghai Jiao Tong University Affiliated First People's Hospital, No. 100, Haining Road, 200080, Shanghai, China. hubinsjtu@163.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, 200233, Shanghai, China. zunqiang1978@hotmail.com.
authors.forename: Zun-Qiang
authors.initials: ZQ
authors.lastname: Zhou
authors.affiliation: Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, 200233, Shanghai, China. 0727guanjiao@163.com.
authors.forename: Jiao
authors.initials: J
authors.lastname: Guan
authors.affiliation: Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, 200233, Shanghai, China. zhengyunzh@yahoo.com.cn.
authors.forename: Zheng-Yun
authors.initials: ZY
authors.lastname: Zhang
authors.affiliation: Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, 200233, Shanghai, China. gwzhousfph@163.com.
authors.forename: Guang-Wen
authors.initials: GW
authors.lastname: Zhou
mesh_terms: D001650:Bile Duct Neoplasms / Q000209:etiology* / Q000473:pathology; D017734:Bile Ducts, Extrahepatic / Q000473:pathology / Q000821:virology*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology / Q000821:virology*; D016022:Case-Control Studies; D018281:Cholangiocarcinoma / Q000209:etiology* / Q000473:pathology; D016174:Hepacivirus / Q000472:pathogenicity*; D006526:Hepatitis C / Q000150:complications* / Q000821:virology; D006801:Humans; D008113:Liver Neoplasms / Q000209:etiology* / Q000473:pathology; D011379:Prognosis