(HEPATOLOGY 2011;) Cholangiocarcinoma (CC) is a malignant neoplasm of the biliary-duct system accounting for 3% of gastrointestinal tumors.1-3 It is the second most common primary hepatic malignancy, representing 10%-25% of primary hepatic malignancies worldwide.1, 4, 5 CC rarely occurs before the age of 40; the typical age at presentation is the seventh decade of life.3, 4 Men have a higher incidence of CC than do women,3, 6-9 with ratios of 1:1.2-1.5. The incidence of CC varies greatly by geographic region secondary to variations in risk factors.3, 5 The prognosis click here of CC is poor;

therefore, mortality and incidence rates are similar. Although there are established risk factors for the development of CC, most patients

do not have an identifiable risk aside from age.1, 4 Anatomically, CC can be classified as intra- or extrahepatic in location.2 Hilar CC (i.e., Klatskin tumors) is typically considered extrahepatic. The distinction between this website intrahepatic CC (ICC) and extrahepatic CC (ECC) has become increasingly important, as the epidemiological feature (i.e., incidence and risk factors) associated with each may be different.1, 2 In this review, we will distinguish between ICC and ECC, because epidemiological differences may exist between them. Otherwise, CC will be used when studies do not distinguish between ICC and ECC. Population-based incidence data on CC are sparse. Most cancer registries combine cases of CC with other hepatobiliary malignancies, such as hepatocellular cancer (HCC) and gallbladder cancer.6, 8 Worldwide, the incidence of CC varies greatly.3,

8 Regions such as Thailand in Southeast Asia have the highest incidence of CC, as high as 113 per 100,000 in men and 50 per 100,000 in women, whereas in Western countries such as Australia, the incidence is low, at 0.2 per 100,000 in men and 0.1 per 100,000 in women.3, 5 Differing exposure to risk factors is thought to account for the varying geographic incidences, with parasitic infections and selleck chemicals llc hepatolithiasis being more prevalent in Asia.3, 5 Several studies published in the early 2000s reported international trends in increased incidence of ICC and decreased incidence of ECC,6, 8 but the role that misclassification of hepatobiliary cancer plays in explaining epidemiological trends may be substantial. The incidence of CC in the United States is reported from the population-based registries of the Surveillance, Epidemiology, and End Results (SEER) program. The age-adjusted annual incidence of ICC increased from 0.13 per 100,000 persons in 1973 to 0.67 per 100,000 in 19977 and to 0.85 per 100,000 persons during 1995-1999 and a decline in ECC incidence from 1.08 per 100,000 in 1979 to 0.82 per 100,000 in 1998.3 However, the recent SEER data from 2000 to 2005 show that the annual incidence of ICC has declined to 0.58 per 100,000 and that of ECC has increased to 0.88 per 100,000.