Furthermore, IL-17 carried by NETs (NETs-IL-17) demonstrated strong predictive value for extrahepatic metastasis in HCC, with an area under the ROC curve (AUC) of 0.89.<h4>Conclusions</h4>A positive feedback loop between neutrophils and macrophages via the NETs-IL-17/VEGF/S100A9 axis accelerates HCC progression and metastasis. This evidence concerns the gene S100A9 and hepatocellular carcinoma.