CEACAM5 and neoplasm: However, there are clinical limits for accurate tumor detection and diagnoses using preoperative examinations such as endoscopy, endoscopic ultrasonography (EUS), computed tomography (CT), and positron emission tomography‐computed tomography.2, 3, 4 Carcinoembryonic antigen (CEA) and carbohydrate antigen 19‐9 (CA19‐9) are now commonly used as established serum markers in the clinical management of patients with gastric cancer.