Liquid‐based cell suspension of supraclavicular lymph node fine‐needle aspirate as an alternative specimen for NGS‐based genomic profiling in advanced lung cancer

Abstract

Our study demonstrates the clinical utility of liquidbased cell suspension of fine-needle aspirates (FNA) of supraclavicular lymph node (SLN) stored in 10% neutral buffered formalin (NBF) as a source of tumor-derived DNA for next-generation sequencing (NGS)-based mutation profiling and guides therapeutic decisions of patients with advanced lung cancer. Over the past decade, various targeted therapies have dramatically improved the survival of patients with advanced lung cancer harboring actionable genetic mutations, making it essential to implement NGS-based molecular profiling in clinical practice to simultaneously interrogate and identify potential tyrosine kinase inhibitor-sensitizing mutations for treatment planning. 1-3 The use of specimens obtained in a less invasive manner, including cytology specimens collected through FNA biopsy has been extensively explored for NGS assays. 2,4-6 SLN metastasis occurs in 26-42% of advanced lung cancer. 7 SLN-FNA prepared as cytospin or formalin-fixed paraffinembedded (FFPE) cell blocks have been reported in PCRbased EGFR mutation testing. 8 Compared to conventional smears, liquid-based cytology maintains the morphology of the collected cells, which preserves DNA integrity and minimizes DNA degradation, thereby improving the quantity and quality of DNA extracted for subsequent molecular assays. 9 Moreover, liquid-based cytology stored in 10% NBF is more convenient for molecular testing applications than FFPE cell blocks by skipping the laborious paraffinization/deparaffinization sample processing steps. SLN-FNA samples stored in 10% NBF were obtained from 54 lung cancer patients with pathologically confirmed metastatic SLNs diagnosed between January 2018 and December 2019 at Fudan University Shanghai Cancer Center, 53 of whom also had paired plasma samples (Figure 1A). The baseline characteristics of these patients were listed in Table S1. DNA from the SLN-FNA samples and This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.