Limitations in the Use of Serum Epidermal Growth Factor Receptor Mutations as Prognostic Markers for Non-Small-Cell Lung Cancer

OBJECTIVES: In this study, we surveyed patients with advanced non-small-cell lung cancer (NSCLC) who were undergoing tyrosine kinase inhibitor (TKI)-targeted therapy. Our aim was to determine whether epidermal growth factor receptor (EGFR) mutations in serum circulating tumor (ct)DNA are useful prognostic markers for NSCLC. SUJECTS AND METHODS: Serum samples were collected from 300 patients with NSCLC that included adenocarcinoma (ADC, n = 155) and squamous cell carcinoma (SCC, n = 145). DNA was extracted from the sera for the nested polymerase chain reaction (PCR) amplification of EGFR exons 18, 19 and 21 mutations. Direct sequencing of the PCR products was carried out in an automated 3730 sequencer. RESULTS: The EGFR exons 18, 19 and 21 were successfully detected in the serum samples of 300 NSCLC patients. No EGFR mutation was found in the blood samples regardless of the characteristics of gender, age, ADC and SCC status or smoking history. CONCLUSION: No mutations in EGFR exons 18, 19 or 21 were identified in the serum ctDNA of these advanced-stage NSCLC patients undergoing TKI-targeted therapy. More studies are needed on the use of EGFR mutations in serum ctDNA as guidance for TKI-targeted therapy.