In hepatocellular carcinoma, the exo_circ_0006602 was a more efficient diagnostic biomarker than the classic tumour serum markers: alpha-fetoprotein (AFP) (AUC = 0.694, p < 0.002) and CEA (AUC = 0.589, p = 0.146). The gene discussed is AFP; the disease is hepatocellular carcinoma.