With the exception of established, relatively nonspecific biomarkers, such as carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9), and cancer antigen 72-4 (CA72-4), there are currently no noninvasive diagnostic, prognostic, or predictive biomarkers that can be detected in the blood of patients with gastric cancer in order to diagnose and stratify patients to receive particular therapies, or for modelling the disease progression. Here, CEACAM5 is linked to cancer.