According to de Groen et al. approximately 67% of biliary tract tumours are gallbladder carcinomas, 22% are hilar carcinomas (Klatskin tumours), 8% occur in the distal bile duct, and 3% are intrahepatic cholangiocarcinomas (ICC). Since 1970 the incidence of ICC is increasing in North America and western Europe, as has been reported by Welzel et al. and West et al.. The cause of this rise is unknown, and does not appear to be explained simply by improvements in diagnosis or changes in coding practice. Besides regional aetiological factors such as liver fluke infection and hepatolithiasis, it has been hypothesized recently by Khan et al. that this increase may be a result of a rise in one or several genotoxic environmental agents, causing cholangiocyte DNA damage.
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