CEACAM5 and gastric cancer: For the operable cases, tumor node metastasis (TNM) staging is the most important for predicting prognosis of gastric cancer so far, but for the metastatic gastric cancer, TNM staging cannot serve as a prognostic factor anymore.4 Now, carcinoembryonic antigen (CEA) is widely used as a monitoring tool for cancer progression of gastric cancer after surgery.5 However, only few data that needs more validation are available.