CEACAM5 and neoplasm: Serum tumor markers are a class of chemicals synthesized and released by tumor cells that can react to cancer hosts.14 Recently, there is a continuous development of molecular biology technology, promoting an extensive application of tumor marker detection clinically, which plays an important role in determining the diagnosis, recurrence and prognosis of malignant tumors.15 Multiple serum tumor markers have been adopted clinically for the diagnosis of colon cancer at present, among which CEA and CA199 are the most common tumor markers in the diagnosis and treatment of colon cancer.