EGFR Mutational Analysis of Non-small Cell Lung Cancer Samples Obtained by Several Procedures

Abstract

Background. Retrospective analyses have been reported on the relationship between mutations in exons 18-21 of the epidermal growth factor receptor (EGFR) gene and response to gefitinb in non-small cell lung cancers (NSCLCs). Objectives. In this study, we evaluated the EGFR mutation rate of NSCLC tumor samples obtained by several procedures and the correlation with response to gefitinib. Subjects. One hundred and seventeen patients with histologically confirmed NSCLCs diagnosed from November 2004 through January 2006 at each institute of the Hokkaido Lung Cancer Clinical Study Group were enrolled. Fifty-two surgically resected samples and 52 transbronchial biopsy (TBB) samples, and 13 other biopsy samples were used for analysis. Methods. Genomic DNA was extracted from tumors of paraffin-embedded tissues. Exons 18-21 of EGFR were amplified by PCR, and the resulting PCR amplicons were directly sequenced. Results. The overall proportion of patients with EGFR mutations were 29% (34/117). There was no significant difference in mutation rate between surgically resected samples (29%, 15/52) and TBB samples (27%, 14/52). Deletions in exon 19 and L858R in exon 21, which are reportedly correlated with gefitinib sensitivity, were detected in 26% of all the samples (30/117), 25% (13/52) of surgically resected samples, and 25% (13/52) of TBB samples, respectively. There was no significant difference either in response rate of gefitinib between surgically resected samples (70%, 7/10) and TBB samples (67%, 8/12). Conclusion. TBB samples are as useful as surgically resected samples in EGFR mutational analysis. (JJSRE. 2006;28:597-600)