The proportion of TIGIT+ T cells in peripheral blood of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HBV-HCC) patients was significantly higher than that in healthy blood donors and hepatitis B virus (HBV)-associated liver cirrhosis (HBV-LC) patients, and the number of TIGIT+CD8+ T cells was positively correlated with tumor recurrence, tumor invasion and mortality of HBV-HCC, and higher frequency of TIGIT+CD8+ T cells was more closely related to poor prognosis of HBV-HCC than that of TIGIT+CD4+ T cells (Liu et al., 2019). This evidence concerns the gene CD4 and hepatocellular carcinoma.