Out of these 33 candidate biomarkers, 20 proteins were identified in proteomic datasets enriched with cancer secretome with 6 proteins namely vitronectin (VTN), inter-alpha-trypsin inhibitor heavy chain family, member 4 (ITIH4), haptoglobin (HP), Histidine-rich glycoprotein (HRG), complement component 4A (C4A) and angiogenin (ANG), being previously studied and characterized as circulating HCC biomarkers. The gene discussed is C4A; the disease is hepatocellular carcinoma.