Compare the molecular differences of pleural effusion and metastatic lymph node biopsy of lung adenocarcinoma based on NGS and evaluate the Clinical efficacy

Objective The present study is to investigate the next-generation sequencing (NGS) molecular typing results of liquid-based cytology specimens (LBCSs) of pleural effusion in lung adenocarcinoma evaluate the clinical efficacy of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) treatment and compare the consistency of the molecular typing results with those of metastatic lymph node biopsy specimens (MLNBSs). Methods A total of 222 cases of lung adenocarcinoma pleural effusion LBCSs and 201 cases of MLNBSs were collected to compare the consistency of NGS molecular typing results. The impacts of different tumor cell contents in LBCSs on mutation detection limitation was evaluated. The clinical efficacy evaluation was performed on 91 patients treated with EGFR-TKI was evaluated and the survival curve analysis was conducted using Kaplan-Meier method. Results The mutation rates of cancer-related genes detected by NGS were comparable LBCSs and MLNBSs of lung adenocarcinoma(82.0% vs 79.1%, P = 0.455). However, the mutation rate of EGFR T790M was significantly higher in pleural effusion LBCSs than in MLNBSs(12.2%>3.5%, P = 0.001). After EGFR-TKI treatment, the mean progression-free survival time (PFS) was 11.4 months in 91 patients with molecular typing based on LBCSs. Conclusions The results of NGS molecular typing of pleural effusion LBCSs from lung adenocarcinoma patients can yield comparable PFS to that of histological specimens following the clinical application of EGFR-TKI treatment.