Clonality status of multifocal lung adenocarcinomas based on the mutation patterns of EGFR and K-ras

PurposeThe purpose of this study is to clarify the clonality status of multifocal lung adenocarcinomas based on the mutation patterns of epidermal growth factor receptor (EGFR) and K-ras.MethodsWe analyzed 82 multifocal lung adenocarcinomas from 36 patients who underwent surgical resection. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue and analyzed for EGFR and K-ras mutations. We determined the clonality status of multifocal lung adenocarcinomas based on the mutation patterns of EGFR and K-ras. The actuarial survival time was estimated and the prognostic factors were evaluated for 31 patients with synchronous multifocal lung adenocarcinomas.ResultsEGFR and K-ras mutations were detected in 36 (44%) and 19 (23%) of the 82 tumors, respectively. EGFR mutations had occurred randomly in 20 (91%) of the 22 patients with at least one EGFR mutated tumor. K-ras mutations had occurred randomly in 14 (93%) of the 15 patients with at least one K-ras mutated tumor. Combining the results for the EGFR and K-ras mutation patterns, the clonality status of multifocal lung adenocarcinomas could be determined in 30 (83%) of the 36 patients. No statistically significant difference in the actuarial survival of the patient subgroups stratified according to the clonality status, which was based on the presence of EGFR and K-ras mutations, was observed.ConclusionsBoth EGFR and K-ras mutations frequently occur randomly in multifocal lung adenocarcinomas. Combined mutation pattern analyses of EGFR and K-ras may be useful for making decisions regarding treatment strategies for patients with multifocal lung adenocarcinomas.