TUMOURS OF THE GALLBLADDER
Cancer of the gallbladder is relatively rare, with an incidence of 2 per 100,000. It is more common in females and has a peak incidence in the seventh decade. Most gallbladder cancers (95 %) are adenocarcinomas, and cholelithiasis appears to be the most important predisposing factor. The frequency is very high in North American aboriginals and commoner in the Japanese and in Caucasian than in negroid races. There is an increased relative risk of this cancer in the first-degree relatives of index cases of up to 14 (Fernandez et al. 1994). Familial clustering is very rare, but two families in which several cases of this disorder occurred were described in Hispanic Indians from New Mexico, perhaps reflecting a higher genetic risk for this cancer in this racial group (Devor and Buechley 1979). Developmental abnormalities of the pancreatobiliary ducts, including choledochal cysts, are associated with malignancy in situ, but these are rarely familial.
Biliary tract cancer appears to occur with increased frequency in Lynch syndrome (Aarnio et al. 1995; Watson et al. 2008).