title: Risk factors for intrahepatic and extrahepatic cholangiocarcinoma: a hospital-based case-control study.
abstract: BACKGROUND
  The risk factors for cholangiocarcinoma are poorly defined in the United States. We evaluated hepatitis C virus (HCV), hepatitis B virus (HBV), and liver cirrhosis as risk factors for intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC).
  
  
  METHODS
  A case-control study in which cases were cholangiocarcinoma patients referred to the M.D. Anderson Cancer Center between 1992 and 2002 and controls were healthy individuals. Information about liver diseases, family history, diabetes, smoking, and alcohol consumption were collected on both groups. Blood from all participants was tested for HBV and HCV markers.
  
  
  RESULTS
  We identified 246 cases (83 ICC and 163 ECC) and matched them to 236 controls. Compared with controls, ICC patients had a higher prevalence of anti-HCV antibodies (6.0%vs 0.8%, P=0.01), anti-HBc (9.6%vs 0%, P<0.0001), and heavy alcohol consumption (21.7%vs 3.8%, P<0.0001). The adjusted odds ratio and 95% confidence interval (CI) were 7.9 (95% CI 1.3-84.5), 28.6 (95% CI 3.9-1,268.1), and 5.9 (95% CI 2.1-17.4), respectively. Only heavy alcohol consumption was higher in patients with ECC than in controls (17.8%vs 3.8%, P=0.003). The prevalence of diabetes and smoking were not significantly different between cases (ICC or ECC) and controls. The prevalence of cirrhosis was higher in patients with ICC than those with ECC (24.1%vs 4.9%, P<0.0001).
  
  
  CONCLUSIONS
  Liver cirrhosis and chronic HCV infection are possible risk factors for ICC but not ECC. Heavy alcohol consumption is a risk factor for both ICC and ECC.
authors.affiliation: The Houston Veterans Affairs Medical Center and Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Yasser H
authors.initials: YH
authors.lastname: Shaib
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Nooka
authors.forename: Melanie
authors.initials: M
authors.lastname: Thomas
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Brown
authors.forename: Yehuda Z
authors.initials: YZ
authors.lastname: Patt
authors.forename: Manal M
authors.initials: MM
authors.lastname: Hassan
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects; D001650:Bile Duct Neoplasms / Q000209:etiology* / Q000821:virology; D017734:Bile Ducts, Extrahepatic; D001653:Bile Ducts, Intrahepatic; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D018281:Cholangiocarcinoma / Q000209:etiology* / Q000821:virology; D005260:Female; D006509:Hepatitis B / Q000150:complications*; D006526:Hepatitis C / Q000150:complications*; D006801:Humans; D008103:Liver Cirrhosis / Q000150:complications*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D018709:Statistics, Nonparametric; D014481:United States