Relationship between types of common channel and development of biliary tract cancer in pancreaticobiliary maljunction.

Background Aims: The incidence of biliary tract cancer development is high among patients with pancreaticobiliary maljunction. However, there have been no reports published evaluating the incidence of development of biliary tract cancers in pancreaticobiliary maljunction based on the morphology of the common channel at the junction of the bile and pancreatic ducts. We evaluated between types of common channel and development, of biliary tract cancers in pancreaticobiliary maljunction. Methodology: During the last 21 years, we have experienced 78 patients with pancreaticobiliary maljunction. Of those patients, 44 adult patients, where morphologic types of common channel were identified by cholangiography, were enrolled in this study. The dilatation patterns of the common channel were classified into 3 types: A type (moderately dilated type), B type (markedly dilated type), and C type (non-dilated type). Evaluated items included the length and dilation patterns of the common channel, incidence of development of biliary tract cancers and proliferative activity in the biliary tract epithelium. Results: Seventeen patients had a common channel shorter than 20mm, while 27 had a common channel of 20mm or longer. Eleven patients with a common channel of 20mm or longer had development of bile tract cancers. The dilation patterns of the common channel were classified as A (11 patients), B (16 patients) and C type (17 patients). Amylase levels in the biliary tract were higher in patients with A and B type than in patients with the C type. Development of gallbladder cancer was observed in 6 patients with A, 2 patients with B and one patient with C, while development of bile duct concer was observed in 2 patients with C and one patient with B. The PCNAL.I. of the biliary epithelium was higher in patients with A, B and C type in descending order. Conclusions: The incidence of development of billary tract cancer was higher in patients with common channel of 20mm or longer. The proliferative activity in the biliary epithelium was accelerated in patients with A type, together with a high incidence of development of gallbladder cancer.