[Analysis of gene detection results of next-generation sequencing of liquid based cytological specimens of lung adenocarcinoma cavity effusion and evaluation of clinical efficacy].

Objective: To analyze the results of next generation sequencing (NGS) gene testing in liquid-based cytological specimens of lung adenocarcinoma cavity and evaluate the clinical efficacy of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment. Methods: Liquid based cytological specimens of 222 cases of lung adenocarcinoma with cavity effusion and 201 cases of metastatic lymph node biopsy were collected. Specimens were obtained from the Cytology Laboratory of the Cancer Hospital of the Chinese Academy of Medical Sciences. The collection period was from January 2018 to December 2022. The results of NGS gene detection were compared. The clinical efficacy of 91 patients treated with EGFR-TKI was evaluated, and the survival curve was analyzed by Kaplan-Meier and other statistical methods. Results: The mutation rates of cancer-related genes detected by NGS were 82.0% (182/222) vs 79.1% (159/201), (P=0.455) in liquid-based cytological specimens and histological specimens of metastatic lymph node biopsy, respectively. However, the mutation rate of EGFR T790M was significantly higher in cavity effusion than in lymph node biopsy specimens [12.2%(27/222)＞3.5%(7/201), P=0.001]. The results of gene mutation were identical in 10 of the 13 cases with cavity effusion and metastatic lymph node biopsy, and the agreement rate of EGFR was 84.6%(11/13). In 3 inconsistent cases, EGFR mutations were detected in 2 cavity effusion cases that were not detected by lymph node biopsy. Results of genetic analysis of fluid-based cytological samples of 91 patients with cavity effusion were evaluated after drug treatment with EGFR-TKI. The mean progression-free survival (PFS) of the patients was 11.4 months (95% CI: 9.9-12.9). The mean PFS of patients harboring EGFR mutation was 12.3 months (95% CI: 10.8-13.9), and the mean PFS of EGFR wild type was 4.1 months (95% CI: 2.1-6.2). Conclusions: The results of NGS gene detection in liquid-based cytological specimens of lung adenocarcinoma patients with cavity effusion show that the PFS time is similar to that of histological specimens after clinical treatment with EGFR-TKI, which proves the reliability of NGS gene detection results in liquid cytological specimens. NGS gene testing appears higher sensitivity in cavity liquid-based samples than in metastatic lymph node samples.