ROC curves of HERV-K (HML-2) expression. (a) HERV-K (HML-2) was considered to be a valuable parameter in the prediction of HCC (AUC = 0.730, 95% CI: 65.21%–80.55%, and P < 0.0001). (b) The predicative value of HERV-K (HML-2) for differentiation of HCC resulted in AUC of 0.678 (95% CI: 50.70%–83.65%, P = 0.041). (c) The significant diagnostic value of HERV-K (HML-2) for TNM stage of HCC (AUC = 0.645, 95% CI: 51.79%–77.27%, and P = 0.030).