Moreover, the measurement of biochemical tumor markers such as cancer antigen 72-4 (CA72-4), carcinoembryonic antigen (CEA) or carbohydrate antigen (CA19-9) concentrations are also very important in the diagnosis of patients with this malignancy; however, these biomarkers cannot be used in the early detection of GC. Here, CEACAM5 is linked to neoplasm.