Descriptive study of gallbladder, extrahepatic bile duct, and ampullary cancers in the United States, 1997-2002.

OBJECTIVE: Few investigations of biliary tract (gallbladder, extrahepatic bile duct, ampulla of Vater) cancers have been conducted because of the relative rarity of these malignancies. The objective of this analysis was to compare the demographic, pathological, and clinical features of biliary tract cancers among men and women.
METHODS: Biliary tract cancers among 11,261 men and 15,722 women were identified through 33 US population-based registries during the period 1997-2002. These registries were estimated to represent 61% of the US population. Age-adjusted incidence rates (AAIR) were calculated per 100,000 population using counts derived from the 2000 US census.
RESULTS: The AAIR for gallbladder cancer among men (0.82 per 100,000) was significantly lower than the AAIR among women (1.45 per 100,000). By contrast, rates for extrahepatic bile duct and ampullary cancers were significantly higher among men (0.93 per 100,000 and 0.70 per 100,000, respectively) than among women (0.61 per 100,000 and 0.45 per 100,000, respectively). White men and women had significantly lower AAIRs for gallbladder cancer compared with other racial-ethnic groups, with the highest rates among Hispanics, American Indian-Alaska Natives, and Asian-Pacific Islanders. Asian-Pacific Islanders and Hispanics of both sexes had the highest AAIRs for extrahepatic bile duct and ampullary cancers. Ampullary tumors were more likely to be diagnosed at a localized or regional stage than were cancers of the gallbladder and extrahepatic bile duct. Asian-Pacific Islander men and women tended to have more unstaged cancers than other groups.
CONCLUSIONS: This population-based study suggests distinct etiologies of anatomic subsites of biliary tract cancer and caution against analytic investigations of all biliary tract cancers combined.