AFP and hepatocellular carcinoma: ROC curve analyses revealed that the combination of AFP mRNA and GPC3 improved diagnostic performance for HCC compared to that of GPC3 alone (Fig. 3b, e and Table 2; NRI = 0.063, p < 0.001 and IDI = 0.103, p < 0.001 in the training cohort and NRI = 0.155, p < 0.001 and IDI = 0.106, p < 0.001 in the validation cohort).