Comparison of Epidermal Growth Factor Receptor Mutations between Primary Tumors and Lymph Nodes in Non-small Cell Lung Cancer: a Review and Meta-analysis of Published Data

Background: Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC)can predict the clinical response to tyrosine kinase inhibitor (TKI) therapy. However, EGFR mutations may bedifferent in primary tumors (PT) and metastatic lymph nodes (MLN). The aim of this study was to compareEGFR mutations between PT and the corresponding MLN in NSCLC patients, and provide some guidelinesfor clinical treatment using TKI therapy. Materials and
Methods: A systematic review and meta-analysis wasperformed with several research databases. Relative risk (RR) with the 95% confidence interval (CI) wereused to investigate the EGFR mutation status between PT and the corresponding MLN. A random-effectsmodel was used.
Results: 9 publications involving 707 patients were included in the analysis. It was found thatactivation of EGFR mutations identified in PT and the corresponding MLN was 26.4% (187/707) and 19.9%(141/707), respectively. The overall discordance rate in our meta-analysis was 12.2% (86/707). The relative risk(RR) for EGFR mutation in PT relative to MLN was 1.33 (95%CI: 1.10-1.60; random-effects model). Therewas no significant heterogeneity between the studies (I2=5%, p=0.003).
Conclusions: There exists a considerabledegree of EGFR mutation discrepancy in NSCLC between PT and corresponding MLN, suggesting that tumorheterogeneity might arise at the molecular level during the process of metastasis.