CEACAM5 and neoplasm: Conventional tumor markers commonly used for adjunctive diagnostic, prognosis, and therapeutic monitoring purposes in EC include cytokeratin-21-1-fragment (CYFRA21-1), carcinoembryonic antigen (CEA), squamous epithelial cell carcinoma antigen (squamous cell carcinoma antigen [SCC]), and tissue polypeptide-specific antigen (TPS), etc. While combined application of these tumor markers may enhance efficiency in the intermediate and advanced stages of EC, the individual sensitivity of them for EC at an early stage is generally below 20%.