CEACAM5 and neoplasm: Traditionally, the tumor infiltration depth, the number of metastatic lymph nodes, tumor location, distant metastasis and completeness of excision, and the levels of postoperative serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) have been used as indicators of prognosis, which are not fully reliable yet [24].