The main findings of this study are that it is possible to use the serum levels of 5 TMs – CEA, CYFRA 21-1, NSE, ProGRP, and SCC, to reduce the uncertainty of the diagnosis of LC and also, to support in the histological differentiation between NSCLC and SCLC. Here, CEACAM5 is linked to laryngotracheoesophageal cleft.