A Nature Communications study from Mass General Brigham reveals that chronic hepatitis B virus (HBV) infection sensitizes the liver to environmental carcinogens, promoting inflammation and hepatocellular carcinoma (HCC). Using a mouse model, researchers demonstrated that HBV alone does not induce liver cancer but amplifies carcinogen-induced tumorigenesis via inflammatory cytokine IL-33. This work redefines the interaction between viral infection and lifestyle factors affecting liver cancer development.