CEACAM5 and neoplasm: In recent years, the research and clinical application of representative tumor markers such as squamous cell carcinoma antigen (SCCAG), neuron-specific enolase (NSE), cytokeratin-19 fragment (CA211), carbohydrate antigen 153 (CA153), matrix metalloproteinases (MMPs) and carcinoembryonic antigen (CEA) are relatively deep and mature.