Intrahepatic and extrahepatic cholangiocarcinomas are rare and highly malignant cancers of the bile duct.
Although the incidence of extrahepatic cholangiocarcinoma has remained constant, the incidence of intrahepatic cholangiocarcinoma has increased in the United States.
Because the etiology of both tumors is poorly understood, Dr Tania Wetzel and colleagues from Maryland, USA conducted a population-based case-control study.
The investigative team examined the association of extrahepatic cholangiocarcinoma and intrahepatic cholangiocarcinoma with preexisting medical conditions.
|Hep C was associated only with intrahepatic cholangiocarcinoma|
|Clinical Gastroenterology and Hepatology|
The team found medical conditions among 535 intrahepatic cholangiocarcinoma patients, and 549 extrahepatic cholangiocarcinoma patients diagnosed between 1993 and 1999.
In addition, the investigators identified 102,782 cancer-free controls by using the Surveillance, Epidemiology and End Results-Medicare databases.
The investigators used logistic regression analysis to calculate adjusted odds ratios.
The team found that, in addition to choledochal cysts, cholangitis, and inflammatory bowel disease, several other conditions were associated cholangiocarcinoma .
Biliary cirrhosis, cholelithiasis, alcoholic liver disease, and nonspecific cirrhosis were all associated with extrahepatic and intrahepatic cholangiocarcinoma.
The team noted that diabetes and thyrotoxicosis were associated with extrahepatic and intrahepatic cholangiocarcinoma.
Chronic pancreatitis was also associated with extrahepatic and intrahepatic cholangiocarcinoma.
The team found conditions associated only with intrahepatic cholangiocarcinoma were obesity, and chronic nonalcoholic liver disease.
The investigators observed that Hepatitis C infection, and smoking were both associated only with intrahepatic cholangiocarcinoma.
Dr Wetzel's team concluded, "Several novel associations with extrahepatic and intrahepatic cholangiocarcinoma were identified."
"Hepatitis C virus infection, chronic nonalcoholic liver disease, and obesity, all of which are increasing in incidence, and smoking were associated only with intrahepatic cholangiocarcinoma."
"This suggests that these conditions might explain the divergent incidence trends of the tumors."