Discordance of Epidermal Growth Factor Receptor Mutations between Primary 
and Corresponding Metastatic Tumors in Non-small Cell Lung Cancer

Background and objective Epidermal growth factor receptor (EGFR) gene mutation assay has been applied to select the chemosensitive patients for tyrosine kinase inhibitor (TKI) treatment widely. The aim of this study is to determine the discordance of EGFR mutations between primary and corresponding metastatic tumors in non-small cell lung cancer (NSCLC). Methods Thirty five paired primary tumors and corresponding metastases from Cancer Center of Sun Yatsen University were evaluated for the EGFR mutations by TaqMan RT-PCR analysis. Results EGFR mutations were detected in 29 of 35 primary tumors and in 18 of 35 corresponding metastases. 31.43% (11 of 35, P=0.008) showed discordance in EGFR mutations between primary tumors and corresponding metastases. The EGFR mutation status was consistent in 68.57% (24 of 35) patients. Conclusion EGFR mutations were discordant between the primary tumor and the corresponding metastases in NSCLC