KITLG and biliary tract neoplasm: Unfortunately, different studies highlighted the extreme variability and a lack of diagnostic ability of TNF-α and ILs for PC compared to biliary tract neoplasm and benign disease, and there is limited published literature concerning the elevated levels of oncostatin M (OSM), CXC motif ligand 8 (CXCL8/IL-8), stem cell factor (SCF), and macrophage colony-stimulating factor in PC [121,122,123].