Risk factors for extrahepatic cholangiocarcinoma: a case-control study in China.

To investigate risk factors for extrahepatic cholangiocarcinoma (ECC) in China. A total of 200 ECC cases and 200 matched control were included in the study. The presence of cigarette smoking, alcohol drinking, choledocholithiasis, primary sclerosing cholangitis, liver fluke infection (Clonorchis sinensis), diabetes mellitus, was investigated through clinical records. Blood from all cases was tested for hepatitis B surface antigen. Odds ratios (OR) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. Compared with controls, ECC patients had a higher prevalence of cigarette smoking (61.0 vs. 47.0%, P=0.007), alcohol drinking (17.5 vs. 3.5%, P<0.000), and choledocholithiasis (6.0 vs. 1.0%, P=0.011). By multivariate analysis, the significant risk factors for the development of ECC were current smoking (OR=1.90, 95% CI=1.08-3.34), heavy alcohol drinking (OR=2.08, 95% CI=1.39-3.13), and choledocholithiasis (OR=6.68, 95% CI=1.48-30.27). The prevalence of hepatitis B virus infection, diabetes mellitus were not significantly different between cases and controls. These findings suggest that smoking, alcohol drinking, and choledocholithiasis are positive risk factors for the development of ECC in China.