Our findings provided evidence for the significant association of TGFB1 gene C-509T polymorphism with hepatocellular carcinoma in population-based studies and circulating TGF-β1 changes, and importantly enhanced circulating TGF-β1 was suggested to be causally associated with an increased risk of hepatocellular carcinoma. The gene discussed is TGFB1; the disease is hepatocellular carcinoma.