Direct Comparison of 3 PCR Methods in Detecting EGFR Mutations in Patients with Advanced Non-Small-Cell Lung Cancer

We compared 3 polymerase chain reaction (PCR) methods (mutant-enriched PCR, peptide nucleic acid-locked nucleic acid [PNA-LNA] PCR, and PCR clamp) to detect EGFR mutations in 50 patients with advanced non-small-cell lung cancer (NSCLC). Seventeen were harboring EGFR mutations, 5 of whom showed discrepancies between the results of different PCR methods. All 5 responded to gefitinib, which we consider to suggest that the discrepancies were false negatives. Background: Epidermal growth factor receptor (EGFR) mutations are predictive of response to EGFR tyrosine kinase inhibitors (TKIs) in NSCLC. Several methods have been used to detect EGFR mutations; however, it is not clear which is the most suitable for use in the clinic. In this study, we directly compare the clinical sensitivity and specificity of 3 PCR methods. Patients and Methods: We compared the 3 PCR methods (mutant-enriched PCR, PNA-LNA PCR, and PCR clamp) in patients with advanced NSCLC. A patient who showed sensitive mutations by at least 1 PCR method was treated with gefitinib. A patient who showed no sensitive mutations was treated with chemotherapy with cytotoxic agents. Results: Fifty patients with advanced NSCLC previously untreated with EGFR-TKIs were enrolled in this trial. Seventeen patients were harboring EGFR mutations, 5 of whom showed discrepancies between the results of different PCR methods. All 5 patients responded to gefitinib. All patients harboring EGFR mutations received gefitinib treatment and 21 of 33 EGFR-mutation-negative patients received chemotherapy with cytotoxic agents. Median progression-free survival of the gefitinib group and the chemotherapy group were 8.2 and 5.9 months, respectively. Conclusion: We considered that all the discrepancies might be false negatives because the patients responded to gefitinib. To clarify the reason for the false negatives of each PCR method, and establish the clinical sensitivity and specificity of each PCR method, a large prospective clinical trial is warranted.