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Introduction: Detection of epidermal growth factor receptor (EGFR) mutation has become the most critical molecular test in managing patients with advanced lung adenocarcinoma. Whether patients with discrepant EGFR mutation results determined by low- and high-sensitivity methods have different clinical outcomes with EGFR tyrosine kinase inhibitor (TKI) treatment needs to be further evaluated., Methods: Genomic DNA from serial lung adenocarcinoma samples that were EGFR wild-type determined by direct sequencing (DS) were reanalyzed using Scorpion/Amplification Refractory Mutation System (ARMS). The outcomes with EGFR-TKI treatment among patients with discrepant EGFR mutation results between DS and Scorpion/ARMS versus patients with EGFR mutations detected by DS were studied., Results: Of the 130 tumors studied, 28 (21.5%) were found to have EGFR mutations by Scorpion/ARMS. Discrepant EGFR mutation testing results were more common in samples from nonsmokers than in samples from smokers (30.7% versus 9.1%; p = 0.003) and in pleural than in nonpleural samples (62.5% versus 18.9%; p = 0.012). There was no significant difference in the abundance of cancer cells in region(s) selected for testing (26.2% in tumor cell percentage ≤50 versus 16.9% in tumor cell percentage >50; p = 0.201). During EGFR-TKI treatment, the progression-free survival in patients with discrepant EGFR mutation results was similar to those with EGFR mutations detected by DS (median, 13.4 versus 10.9 months; p = 0.225)., Conclusions: DS overlooked EGFR mutation in a significant number of lung adenocarcinoma patients. These patients could have obtained the same benefit from EGFR-TKI when a high-sensitivity method such as Scorpion/ARMS was applied.

Background and Objective: Therapeutic responses of lung adenocarcinoma patients to tyrosine kinase inhibitors (TKIs) of epidermal growth factor receptor (EGFR) are closely associated with activating mutations within the EGFR tyrosine kinase domain. Screening activating EGFR mutations prior to selection for therapeutic strategy has been considered extremely valuable for clinical management of lung adenocarcinoma patients in Asian countries including Taiwan, where the EGFR mutation rate is higher than in the rest of the world. Currently there is no consensus on the method of choice to assess EGFR mutations in tumour tissue., Methods: We enrolled 445 lung adenocarcinoma patients for analysis of tumour EGFR mutations using polymerase chain reaction (PCR)-direct sequencing, scorpion/amplified refractory mutation system (ARMS) technology and immunohistochemistry with mutation-specific antibodies., Results: Two hundred forty-five patients (245/445; 55%) were found to harbour activating EGFR mutations using PCR-direct sequencing method, with a majority of patients (233/245; 95%) carrying exon 19 deletion or p.L858R point mutations. One hundred three of 200 patients were negative for EGFR mutations from PCR-direct sequencing were further analysed using Scorpion/ARMS technology. Up to 30% of the PCR-direct sequencing negative patients turned out to be positive in the Scorpion/ARMS EGFR mutation tests. For immunohistochemistry analysis of EGFR mutations, the p.E746_A750del specific antibody showed a sensitivity of 57% and a specificity of 100% for exon 19 deletions while the p.L858R point mutation specific antibody showed a sensitivity of 68% and a specificity of 95%., Conclusions: Based on this study, we proposed an algorithm for comprehensive and efficient testing of EGFR mutations on lung adenocarcinoma patients in Asia., (© 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.)