GEOGRAPHIC CLUSTERING PATTERNS IN MORTALITY FROM BILIARY-TRACT CANCERIN JAPAN

We calculated the standardized mortality ratios (SMRs) of biliary trac t cancer (BTC) in Japan from 1981 to 1990 and statistically analyzed t he results according to 333 Secondary Areas of Medical Care, as well a s ses and subsite [gallbladder cancer (GBC) and extrahepatic bile duct cancer (BDC)], in order to examine geographic clustering patterns of BTC. In GBC in both sexes, the Secondary Areas of Medical Care with hi gh SMRs were clustered in the eastern part of Japan, In BDC in both se xes, the Areas with high SMRs were clustered between the northern and eastern parts of Japan, In comparison with GBC, this clustering favore d the northern part of Japan, In males, the clustering pattern in mort ality from BTC was mainly due to the occurrence of BDC, In females, th e clustering pattern in mortality from BTC reflected that of GBC, The clustering of BTC, especially GBC, seems to be related to the distribu tion of plains, basins, and rivers.