ENO2 and laryngotracheoesophageal cleft: Immunoassay is inexpensive and allows for the analysis of a large number of samples, but the analysis of NSCLC-specific markers, such as CEA (carcinoembryonic antigen), NSE (neuron-specific enolase), CYFRA 21-1 (a soluble fragment of cytokeratin 19 associated with epithelial cell tumors), and SCCA (squamous cell carcinoma antigen), does not have sufficient sensitivity and specificity for early LC detection [14].