Comparison of EGFR mutation status between plasma and tumor tissue in non-small cell lung cancer using the Scorpion ARMS method and the possible prognostic significance of plasma EGFR mutation status.

BACKGROUND The aims were to compare the consistency of epidermal growth factor receptor (EGFR) mutations in the plasma and tumor tissue of NSCLC patients, and to explore the prognostic significance of plasma EGFR mutation status in tyrosine kinase inhibitors (TKIs)-treated patients with tumor EGFR mutation. METHODS We evaluated EGFR gene (exons 18, 19, 20 and 21) mutation status in paired plasma and tumor tissue from 94 NSCLC patients before EGFR-TKIs treatments using the Scorpion amplification refractory mutation system (Scorpion-ARMS) method. RESULTS Our results demonstrated that the rates for EGFR mutations in 94 NSCLC patients were 20% (19/94, plasma samples) and 40% (38/94, tumor tissue samples), respectively. The consistency of EGFR mutations between plasma and tissue reached 80% (75/94, P<0.001). The sensitivity of tests using plasma samples was 50% (19/38) and the specificity was 100% (49/49) compared with tissue samples. 29 of the 38 patients were treated with TKIs. Among the 29 patients, 14 patients had EGFR mutations in both plasma and tumor tissue, and these patients had a significantly shorter overall survival (OS) than those with EGFR mutations in tumor tissue only by univariate analysis (P=0.019). CONCLUSIONS Our data demonstrated the feasibility and potential utility of plasma cell-free DNA (cfDNA) as a source of specimens for EGFR mutation detection using the Scorpion ARMS method. Moreover, plasma EGFR mutation status before TKIs therapy might be of prognostic significance for TKIs-treated NSCLC patients with tumor tissue EGFR mutation.