The cumulative rates of HCC development according to the serum soluble inducible T-cell co-stimulator (sICOS) level are shown in Fig. 1A. The cumulative rates of HCC development at 3, 5, 7, and 10 years were 9.5%, 20.3%, 24.1%, and 27.9%, respectively, in patients with sICOS ≥ 164.71 pg/mL (n = 33), and 2.6%, 4.3%, 8.1%, and 8.1%, respectively, in those with sICOS < 164.71 pg/mL (n = 89) (p = 0.014). This evidence concerns the gene ICOS and hepatocellular carcinoma.