Geographical distribution of biliary tract cancer in Niigata prefecture.

We reviewed 1074 surgically treated patients with biliary tract cancer (gallbladder 564, bile duct 510) in Niigata prefecture in the five-year period from 1982 to 1986. Analyses of regional distributions revealed the incidence of gallbladder cancer to be highest in the Ka-etsu district (northern part of prefecture) and lowest in the Jo-etsu district (south-western part of prefecture). The incidence of bile duct cancer was highest in the district controlled by the most northern public health center and lowest in Chu-etsu district (central part of prefecture). The incidences of gallbladder and bile duct cancers showed regional variations within the prefecture, localization being more pronounced for gallbladder cancer.