Comparison of three methods for detecting epidermal growth factor receptor mutations in plasma DNA samples of Chinese patients with advanced non-small cell lung cancer.

Abstract

e18017 Background: Detecting epidermal growth factor receptor (EGFR) mutations in plasma DNA samples in patients with advanced non-small cell lung cancer is challenging and promising. We compared three methods for detecting plasma EGFR mutations, including direct DNA sequencing, denaturing high-performance liquid chromatography (DHPLC) and Scorpions amplification refractory mutation system (Scorpions ARMS). Methods: Plasma DNA samples from 73 patients with stages IIIB to IV non-small cell lung cancer patients with adenocarcinoma histology were analyzed for EGFR mutations in exons 19 (deletion mutation) and 21 (L858R mutation) by using direct DNA sequencing, DHPLC and Scorpions ARMS . Results: In 73 patients, we detected EGFR mutations in 5 samples (6.85%) by direct DNA sequencing, in 22 samples (30.1%) by DHPLC, and in 28 samples (38.4%) by Scorpions ARMS. we found 13 deletion mutations and 9 L858R mutations by DHPLC, while 15 deletion mutations and 13 L858R mutations by Scorpions ARMS. Among the 73 patients, there was 90.4% concordance between DHPLC and Scorpions ARMS (66/73, κ = 0.71, p < 0.01). Seven patients were detected discordant mutation status by DHPLC and Scorpions ARMS. Six EGFR mutation-positive samples detected by Scorpions ARMS were found mutation-negative by DHPLC, and one EGFR mutation-positive sample detected by DHPLC was found mutation-negative by Scorpions ARMS. In the 73 patients, 46 patients were treated with gefitinib or erlotinib, including 18 patients with mutations and 28 patients without mutations by Scorpions ARMS. The 18 patients with EGFR mutations had a significant longer progression-free survival (PFS) time (median PFS, 21.0 months; 95% confidence interval [CI] 7.5 to 34.5 months) than 28 patients without EGFR mutations (median PFS, 7.0 months; 95% confidence interval [CI] 3.4 to 10.6 months) (p = 0.022). Conclusions: Among the three methods for detecting EGFR mutations in plasma DNA samples in patients with advanced lung adenocarcinoma, direct gene sequencing had the lowest sensitivity, while Scorpion ARMS showed the highest mutation detecting capability. DHPLC is slightly less sensitive than Scorpion ARMS. No significant financial relationships to disclose.