Risk of hepatobiliary and pancreatic cancers after hepatitis C virus infection: A population-based study of U.S. veterans.

UNLABELLED: Hepatitis C virus (HCV) may increase the risk of hepatopancreaticobiliary tumors other than hepatocellular carcinoma (HCC). Previous case control studies indicated a possible association between HCV and intrahepatic cholangiocarcinoma (ICC). Little is known about the association between HCV and extrahepatic cholangiocarcinoma (ECC) or pancreatic cancer. We conducted a cohort study including 146,394 HCV-infected and 572,293 HCV-uninfected patients who received care at Veterans Affairs health care facilities. Patients with two visits between 1996 and 2004 with HCV infection were included, as were up to four matched HCV-uninfected subjects for each HCV-infected subject. Risks of ICC, ECC, pancreatic cancer, and HCC were assessed using proportional hazards regression. In the 1.37 million person-years of follow-up, which began 6 months after the baseline visit, there were 75 cases of ECC, 37 cases of ICC, 617 cases of pancreatic cancer, and 1679 cases of HCC. As expected, the risk of HCC associated with HCV was very high (hazard ratio [HR], 15.09; 95% confidence interval [95% CI], 13.44, 16.94). Risk for ICC was elevated with HCV infection 2.55; 1.31, 4.95), but risk for ECC was not significantly increased (1.50; 0.60, 1.85). Adjustments for cirrhosis, diabetes, inflammatory bowel disease, hepatitis B, alcoholism, and alcoholic liver disease did not reduce the risk for ICC below twofold. The risk of pancreatic cancer was slightly elevated (1.23; 1.02, 1.49), but was attenuated after adjusting for alcohol use, pancreatitis, and other variables.
CONCLUSIONS: Findings indicated that HCV infection conferred a more than twofold elevated risk of ICC. Absence of an association with ECC was consistent in adjusted and unadjusted models. A significant association with pancreatic cancer was erased by alcohol use and other variables.