AFP and hepatocellular carcinoma: Expression levels of serum miR-21 were significantly higher in HCC patients than in controls with an AUC of 0.849, a sensitivity of 82.1%, and a specificity of 83.9%; this finding was true even in AFP-negative HCC subgroups, with an AUC of 0.831, a sensitivity of 81.2%, and a specificity of 83.2%.