Chao-Hua Chiu1, Hsiang-Ling Ho, Chi-Lu Chiang, Shiou-Fu Lin, Hsiu-Hsun Ma, Yu-Ting Chuang, Kun-Yang Lin, Chun-Ming Tsai, Teh-Ying Chou. 1. *Institute of Clinical Medicine and †Department of Medicine, National Yang-Ming University, Taipei, Taiwan; ‡Division of Thoracic Oncology, Department of Chest Medicine and §Division of Molecular Pathology, Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; and ‖Department of Pathology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
Abstract
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.
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 adenocarcinomapatients. These patients could have obtained the same benefit from EGFR-TKI when a high-sensitivity method such as Scorpion/ARMS was applied.