Patients with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are at significant risk for hepatocellular carcinoma (HCC). The most important risk factor associated with HCC is liver cirrhosis, which is again predominantly caused by chronic HBV or HCV infection. The most effective approach to avoid HCC development is to prevent HBV and HCV infection through vaccination. Indeed, HBV vaccine is the first vaccine demonstrated to prevent cancers. However, a vaccine for HCV is

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... t available. Thus, the prevention of HCV-related HCC and to a large extent HBVrelated HCC (among persons who are already chronically infected) will rely on antiviral therapy to prevent progressive liver disease. The evidence that these patients can effectively be protected against HCC risk by the treatment with antiviral therapy is rather controversial, due to the lack of randomized controlled trials (RCTs) that are ideally needed to establish the effi cacy, but are logistically and ethically challenging. Although the strongest evidence to support that antiviral therapy can prevent HCC should be derived from RCTs with HCC as an endpoint, it should be emphasized that clinical trials showing the efficacy of antiviral therapy on virus suppression or eradication, and/or improvement in liver histology can be considered indirect evidence that antiviral therapy can prevent HCC because high virus levels (in the case of HBV infection) and cirrhosis (in both HBV and HCV infection) are the most important risk factors for HCC.