Trends in biliary tract cancer.

Incidence data from a large number of cancer registries throughout the world are presented for cancers at various sub-sites of the biliary tract, to assess whether the epidemiology of gall bladder cancer can be distinguished from cancer of the extra-hepatic bile ducts and cancer of the ampulla of Vater. Cancers of the biliary tract appear to be strongly sex-related. A marked genetic susceptibility emerges from this review, not only for gall bladder cancer, as previously reported for American Indians, but also perhaps for cancer of the extrahepatic bile ducts, for which Japanese of both sexes have high rates. Mortality data for all biliary tract (mainly gall bladder) cancer are examined for the period 1958-85. A wide range of trends is observed, notably a consistent decline in mortality among Anglo-Saxon populations, for both males and females. Dietary factors, possibly mediated through hormonal and genetic factors, are suggested as a major causal influence on biliary tract cancers.