CEACAM5 and cancer: In the clinical field, prognostic biomarkers are often used for treatment decision‐making, because they are known to be useful predictors of outcome in cancer patients.3 In fact, the neutrophil‐to‐lymphocyte ratio (NLR),4 carcinoembryonic antigen (CEA),5 and carbohydrate antigen 19‐9 (CA19‐9)5 have been broadly used as prognostic biomarkers for patients with CRC.