Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are the standard first-line treatment regimen for EGFR mutated non-small cell lung cancer (NSCLC) patients.However, the efficacy of EGFR-TKIs widely varies.The aim of this study is to determine whether the pretreatment serum cytokeratin-19 fragments (CYFRA21-1) and carcinoembryonic antigen (CEA) are associated with the efficacy of EGFR-TKIs in EGFR-mutated NSCLC patients. Here, KRT19 is linked to non-small cell lung carcinoma.