SPP1 and hepatocellular carcinoma: AFP (> 20 IU/ml) had a greater area under the ROC curve (AUROC 0.83; 95% CI 0.77–0.89) than MDK (0.70; 95% CI 0.63–0.76) and OPN (0.65; 95% CI 0.57–0.73) (Fig 2A), suggesting that AFP is superior to these biomarkers for HCC diagnosis.