title: Combined hepatocellular cholangiocarcinomas; analysis of a large database.
abstract: OBJECTIVE
  Combined hepatocellular cholangiocarcinoma (combined tumor) has been described as either a variant of hepatoma or a variant of cholangiocarcinoma. Prior studies evaluated fewer than 50 patients with combined tumors, precluding multivariate analyses. Posited was the notion that analysis of a large database would yield more definite answers.
  
  
  METHODS
  This study used SEER (Surveillance, Epidemiology, and End Results Program of the National Cancer Institute) to analyze 282 combined tumors, 2,035 intrahepatic cholangiocarcinomas, and 19,336 hepatomas between the years 1973-2003. Multinomial logit regression calculated point estimates and 95% confidence intervals (c.i.) for relative risk (rr). Cox regression calculated point estimates and 95% confidence intervals (c.i.) for hazard ratios (ĥ).
  
  
  RESULTS
  Men less often had cholangiocarcinomas than they had combined tumors (rr = 0.63, c.i. = 0.49-0.81). Hepatomas less often than combined tumors presented with distant spread (rr = 0.56, c.i. = 0.43-0.72). Men (rr = 1.50, c.i. = 1.17-1.93) and patients with a known Asian or Pacific birthplace (rr = 2.36, c.i. = 1.56-3.56) more often had hepatomas than they had combined tumors. Among patients not known to have an Asian/Pacific birthplace, a diagnosis of cholangiocarcinoma (ĥ = 0.72, c.i. = 0.63-0.82) or hepatoma (ĥ = 0.75, c.i. = 0.66-0.86) provided a better prognosis than did a diagnosis of combined tumor.
  
  
  CONCLUSIONS
  Combined tumors differ from hepatomas and cholangiocarcinomas in terms of distribution and survival patterns in the population; they should be considered neither cholangiocarcinomas nor hepatomas.
authors.affiliation: Department of Pathology.
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Wachtel
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Tom
authors.initials: T
authors.lastname: Xu
authors.forename: Maurizio
authors.initials: M
authors.lastname: Chiriva-Internati
authors.forename: Eldo E
authors.initials: EE
authors.lastname: Frezza