CEACAM5 and gastric cancer: Currently, the biomarkers used to screen for GC such as glycoprotein chain antigen 125 (CA125), CA19-9, CA72-4, pepsinogen I/II ratio (PG I/PG II), gastrin-17 (G-17), anti-gastric parietal cell antibodies (APCA), squamous cell carcinoma antigen (SCCA), cytokeratin 19 fragment (CYFRA 21-1), and carcinoembryonic antigen (CEA) are found to be not sensitive and specific enough during the time of diagnosis, as reported by studies (3, 102, 103).