Extrahepatic cancers and chronic HCV infection.

Infectious agents, such as HCV, account for ∼15% of human cancers. HCV infects not only hepatocytes but also extrahepatic cells. Chronic HCV infection can induce chronic inflammation with qualitative and quantitative alterations of the immune repertoire and tissue microenvironment, which could induce various neoplasias. Epidemiological studies and meta-analyses suggest an increased rate of extrahepatic cancers in patients with chronic HCV infection along with a higher risk of intrahepatic cholangiocarcinoma, pancreatic cancer and non-Hodgkin lymphoma (NHL), highlighting the need to screen for HCV infection in patients with these cancers. Development of B cell NHL has been associated with HCV infection, with a relative risk of ∼1.5. Direct transformation related to the presence of the virus and chronic antigenic stimulation are the two major non-exclusive mechanisms involved in HCV-related lymphomagenesis. HCV infection alters survival of patients with lymphoma, and sustained virologic response (SVR) substantially improves prognosis. Antiviral treatments might induce remission of indolent lymphoma when SVR is achieved even without chemotherapy, emphasizing the role of HCV in lymphomagenesis in this context. However, studies are needed to provide prospective evidence of a causal relationship between chronic HCV infection and other extrahepatic cancers and to determine whether the risk of extrahepatic cancers is reduced with SVR. In this Review, we report on recent studies analysing the risk of extrahepatic cancers associated with chronic HCV infection. Although there is no doubt regarding the direct and indirect causality between HCV and NHL, an increased risk of other cancers is less clear, with the exception of cholangiocarcinoma.