Clinical Utility of Circulating Tumor DNA for Detecting Lung Cancer Mutations by Targeted Next‐Generation Sequencing With Insufficient Tumor Samples

Abstract

BackgroundCirculating tumor deoxyribonucleic acid (ctDNA) is increasingly applied in clinical practice. This study aimed to explore clinical utility of a minimal invasive and sensitive way of ctDNA for next‐generation sequencing in non–small cell lung cancer (NSCLC) with inadequate tumor samples.MethodsTargeted DNA sequencing was performed on tissue biopsies and matched plasma samples from 60 patients with NSCLC.ResultsA total of 13 driving genes were detected in 60 matched tissue DNA (tDNA) and ctDNA samples. Overall concordance rate was 75.47%, with 77.55% sensitivity and 50% specificity. Epidermal growth factor receptor (EGFR) mutations were the most common in both tDNA and ctDNA samples. Among other mutated genes were tumor protein p53 (TP53), erb‐b2 receptor tyrosine kinase 2 (ERBB2), anaplastic lymphoma kinase (ALK), cyclin‐dependent kinase inhibitor 2A (CDKN2A), ros proto‐oncogene 1, and receptor tyrosine kinase (ROS1). Mutations in b‐raf proto‐oncogene, serine/threonine kinase (BRAF), cluster of differentiation 274 (CD274), neurotrophin receptor tyrosine kinase 1 (NTRK1), and rearranged during transfection (RET) occurred only in plasma. The majority of mutations in both samples were single‐nucleotide variants. Deletions were found in EGFR, BRAF, and TP53 in ctDNA, whereas in tDNA, deletions were only found in EGFR. In ALK, single nucleic acid‐site amplification occurred simultaneously in tissue and plasma, but insertions and copy number variations were detected only in plasma.ConclusionsIdentifying ctDNA mutations by targeted sequencing in plasma is feasible, showing the clinical value of ctDNA‐targeted sequencing in NSCLC patients when tumor tissue sampling is insufficient or even impossible.