The risk of a rare form of liver cancer called intrahepatic cholangiocarcinoma, which occurs in the bile ducts of the liver, is significantly elevated in individuals who are infected with hepatitis C virus (HCV), according to a large “case-control” study of US veterans.

HCV-infected individuals are also at increased risk for another type of liver cancer called hepatocellular carcinoma, the study shows. Liver cancer is the third leading cause of cancer deaths worldwide.

The findings stem from a look at 146,394 HCV-infected and 572,293 uninfected adults, mostly men, who were followed for an average of more than 2 years.

When comparing HCV-infected with HCV-uninfected subjects, the risk of hepatocellular carcinoma was 15-fold higher in the infected group and the risk of intrahepatic cholangiocarcinoma was 2.5-fold higher. The risk of pancreatic cancer was 23 percent higher.

Analyses adjusting for other variables, such as alcohol use and inflammation of the pancreas), confirmed the strong association between HCV infection and hepatocellular carcinoma and intrahepatic cholangiocarcinoma. However, the association between HCV and pancreatic cancer was no longer statistically significant.

Dr. Hashem B. El-Serag, at the Houston VA Medical Center, and colleagues there and at the National Cancer Institute in Rockville, Maryland, say the mixed findings of this study regarding the association between HCV and pancreatic cancer “merit additional investigation.”

“From a clinical perspective,” they conclude, “early intervention strategies, including screening HCV-positive individuals earlier or more rigorously, may improve the outcomes for both hepatocellular carcinoma and intrahepatic cholangiocarcinoma.”

SOURCE: Hepatology, January 2009.