There is no very specific serum tumor marker for colon cancer, and the main serum tumor marker currently used clinically to aid in the diagnosis and prognosis of colon cancer is carcinoembryonic antigen (CEA). CEA is the first serum tumor marker reported to have relevance to colon cancer, and is currently the only molecular marker recommended for routine clinical testing of colon cancer patients. Pre-surgical testing of CEA serum concentrations can predict patient prognosis, and post-surgical and post-treatment testing can be used to monitor recurrence and determine treatment efficacy. In addition, cancer antigen CA19-9, i.e. CA19-9, cancer antigen 24-2, cancer antigen 50, and cancer antigen 74-2 are also commonly used clinically as serum tumor markers to determine the prognosis and judge the efficacy of colon cancer, as well as to aid in diagnosis. However, the specificity and sensitivity of the above indexes are far less than those of CEA, and it is suggested that combined testing with CEA can greatly improve the specificity and sensitivity.