At present, several proteins such as carcinoembryonic antigen, carbohydrate antigen 19–9, cytokeratin 19 fragment antigen 21–1, squamous cell carcinoma antigen, and carbohydrate antigen 72–4 are generally applied as a diagnosis, as well as prognostic predictors for various cancers[34-36], including ESCC[37,38]. Here, CEACAM5 is linked to esophageal squamous cell carcinoma.