CEACAM5 and gastric cancer: As shown in Table 4, hsa_circ_000780 expression levels in GC tissue samples were significantly correlated with tumor size (P = 0.020), tumor stage (P = 0.001), T stage (P = 0.029), venous invasion (P = 0.042), carcinoembryonic antigen (CEA) levels (P = 0.001), and carbohydrate antigen 19-9 (CA19-9) levels (P = 0.001).