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MA05 - Innovative Techniques in Pulmonology and the Impact on Lung Cancer (ID 378)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Pulmonology
- Presentations: 1
MA05.03 - A Single EBUS-TBNA Pass Yields Sufficient DNA for Targeted Molecular Testing in Lung Cancer (ID 4682)
16:00 - 17:30 | Author(s): D.P. Steinfort
Development of drugs that target molecular pathways in lung cancer has made it increasingly important for diagnostic sampling to yield sufficient material for genotyping. At the same time, minimally invasive sampling techniques such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) result in smaller volume cytological specimens. It has been shown that at least 3 EBUS-TBNA passes per lesion are sufficient for cytological subtyping. However, the number of passes needed for mutational subtyping is unclear. We sought to determine the adequacy of a single EBUS-TBNA for genotyping clinically actionable mutations.
Patients undergoing EBUS-TBNA for diagnosis of lung cancer were prospectively recruited. Paired samples from the same target lesion were obtained. The “reference” sample was the routine diagnostic specimen consisting of ≥3 passes, whereas the “study” sample comprised a single pass. DNA was extracted from both samples and subjected to quantitative and qualitative assessment. Sequencing for EGFR, KRAS, BRAF mutations was performed in adenocarcinoma/non-small cell lung cancer not otherwise specified (NSCLC-NOS) cases.
Samples were obtain in 41 patients. Cytological diagnosis was adenocarcinoma/NSCLC-NOS in 25 (61.0%), squamous cell carcinoma in 10 (24.4%), small cell lung cancer in 5 (12.2%), and carcinoid in 1 (2.4%) case. DNA extraction yielded a mean of 4.03μg, well above the minimum required quantity for targeted sequencing of 10ng (Table 1). DNA quality measured by DNA Integrity Number could be calculated in 35 (85%) cases with a mean of 8.9, where >7 is acceptable for sequencing (Table 1). Sequencing results of adenocarcinoma/NSCLC-NOS cases show mutations in EGFR in 6, KRAS in 8, BRAF in 1 case. Wild type was demonstrated in 6 cases. Molecular analysis of the corresponding study samples is proceeding.
Table 1. DNA quantity and quality
Histological subtype Cases, n (%) Mean DNA quantity (μg) Mean DNA Integrity Number (DIN) Adenocarcinoma/NSCLC-NOS 25 (61.0) 3.83 8.8 Squamous cell carcinoma 10 (24.4) 2.65 9.0 Small cell lung carcinoma 5 (12.2) 5.28 9.0 Carcinoid 1 (2.4) 16.24 9.1 Overall 41 4.03 8.9
A single EBUS-TBNA yields DNA of quantity and quality sufficient for molecular analysis, and is expected to be adequate for lung cancer genotyping.
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