Author(s): Santis G, Angell R, Nickless G, Quinn A, Herbert A,
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Abstract EGFR mutations correlate with improved clinical outcome whereas KRAS mutations are associated with lack of response to tyrosine kinase inhibitors in patients with non-small cell lung cancer (NSCLC). Endobronchial ultrasound (EBUS)-transbronchial needle aspiration (TBNA) is being increasingly used in the management of NSCLC. Co-amplification at lower denaturation temperature (COLD)-polymerase chain reaction (PCR) (COLD-PCR) is a sensitive assay for the detection of genetic mutations in solid tumours. This study assessed the feasibility of using COLD-PCR to screen for EGFR and KRAS mutations in cytology samples obtained by EBUS-TBNA in routine clinical practice. Samples obtained from NSCLC patients undergoing EBUS-TBNA were evaluated according to our standard clinical protocols. DNA extracted from these samples was subjected to COLD-PCR to amplify exons 18-21 of EGFR and exons two and three of KRAS followed by direct sequencing. Mutation analysis was performed in 131 of 132 (99.3\%) NSCLC patients (70F/62M) with confirmed lymph node metastases (94/132 (71.2\%) adenocarcinoma; 17/132 (12.8\%) squamous cell; 2/132 (0.15\%) large cell neuroendocrine; 1/132 (0.07\%) large cell carcinoma; 18/132 (13.6\%) NSCL-not otherwise specified (NOS)). Molecular analysis of all EGFR and KRAS target sequences was achieved in 126 of 132 (95.5\%) and 130 of 132 (98.4\%) of cases respectively. EGFR mutations were identified in 13 (10.5\%) of fully evaluated cases (11 in adenocarcinoma and two in NSCLC-NOS) including two novel mutations. KRAS mutations were identified in 23 (17.5\%) of fully analysed patient samples (18 adenocarcinoma and five NSCLC-NOS). We conclude that EBUS-TBNA of lymph nodes infiltrated by NSCLC can provide sufficient tumour material for EGFR and KRAS mutation analysis in most patients, and that COLD-PCR and sequencing is a robust screening assay for EGFR and KRAS mutation analysis in this clinical context.
This article was published in PLoS One
and referenced in Journal of Molecular Biomarkers & Diagnosis