EGFR and KRAS mutation analyses from specimens obtained by bronchoscopy and EBUS-TBNA

Procurement of tumor tissue is mandatory for a mutation analysis in patients with non-small cell lung cancer. The purpose of this study was to evaluate the usefulness of bronchoscopic biopsy and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) biopsy for detecting epidermal growth factor receptor (EGFR) and KRAS mutations in routine practice.

Tumor DNA was extracted from formalin-fixed paraffin-embedded tissues, and amplifications of exons 18-21 of EGFR and codons 12, 13 and 61 of KRAS were performed using polymerase chain reaction (PCR). PCR products were subjected to direct sequencing in both directions.

Of 211 consecutive specimens, 201 (95.3%) were available for EGFR mutation analysis, and 196 (92.9%) were adequate for KRAS mutation analysis. EGFR and KRAS mutations were detected in 14.9% and 5.4%, respectively. A median of 16 days was spent from biopsy to the final report for either EGFR or KRAS mutation status. The detection rates for both mutations were similar between bronchoscopic biopsy and EBUS-TBNA (P > 0.05). Female gender (53.3%), never smoker (63.3%), and adenocarcinoma (96.7%) were predominant in patients with EGFR mutations. Among patients with adenocarcinoma (n = 104), the frequencies of EGFR and KRAS mutations were 27.9% and 10.6%, respectively.

Small tissue samples obtained by bronchoscopic biopsy and EBUS-TBNA are sufficient for detecting EGFR and KRAS mutations in routine practice. Therefore, concurrent mutational analyses of small tissue samples should be considered at the time of initial diagnosis.