Are secondary bile acids in choledochal cysts important as a risk factor in biliary tract carcinoma?

Since secondary bile acids have mutagenic potency and choledochal cyst patients with or without cyst-enterostomy have a high risk of developing bile duct carcinoma, we examined the hypothesis that secondary bile acids are elevated in the choledochal cyst and possibly cause biliary tract carcinoma. Eleven choledochal cyst patients with or without previous cyst-enterostomy or biliary tract carcinoma, seven patients with biliary tract carcinoma not associated with choledochal cyst and five patients with cholecystolithiasis were examined. Samples were directly needle aspirated from the cyst or by cannulating a tube into the common bile duct through the cystic duct. The concentrations of each bile acid in these samples were quantified by gas-liquid chromatography and compared. Neither the relative composition nor the absolute concentration of secondary bile acids (deoxycholic acid, lithocholic acid) elevated in patients with choledochal cyst compared with the values in the non-choledochal cyst patients with or without biliary tract carcinoma. The presence of biliary tract carcinoma or previous cyst-enterostomy did not affect the concentrations of secondary bile acids. The results suggest that the factor other than secondary bile acids can be primarily responsible for the high risk of bile duct carcinoma in patients with choledochal cyst.