CEACAM5 and lung cancer: As we know, tumor markers have been widely used in the detection of lung cancer in recent years, such as progastrin-releasing peptide (ProGRP), vascular endothelial growth factor (VEGF), carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA21-1) and neuronspecific enolase (NSE) [16, 17].