A meta-analysis of case-control studies on the combined effect of hepatitis B and C virus infections in causing hepatocellular carcinoma in China

We investigated whether concurrent infection by hepatitis B virus ( HBV) and hepatitis C virus ( HCV) in China, a hyperepidemic area for these infections, was associated with a higher risk of causing hepatocellular carcinoma ( HCC) than each infection alone in a metaanalysis in China, 32 case - control studies involving 3201 cases and 4005 controls, identified from a computer- based literature search from 1966 to 2004. The pooled odds ratio and 95% confidence interval ( CI) for HBsAg positivity was 14.1 ( 95% CI: 10.6 - 18.8); for anti- HCV/ HCV RNA positivity was 4.6 ( 95% CI: 3.6 - 5.9); for HBsAg positivity and anti- HCV/ HCV RNA negativity were 15.6 ( 95% CI: 11.5 - 21.3); for HBsAg negativity and anti- HCV/ HCV RNA positivity were 8.1 ( 95% CI: 5.0 - 13.0); and positivity for both HBsAg and anti- HCV/ HCV RNA was 35.7 ( 95% CI: 26.2 - 48.5). We conclude that HBV and HCV infections are important independent risk factors for HCC in China, and that dual infection by HBV and HCV is associated with a higher risk of causing HCC than each infection alone, suggesting a synergism between HBV and HCV.