Objective: To evaluate the feasibility of cell-free tumor DNA in pleural effusion supernatant for assessing the tumor mutational burden (TMB) of advanced lung cancers. Methods: From December 2016 to August 2018, 34 lung cancer patients (19 males and 15 females) with pleural effusion were enrolled at Zhongshan Hospital, Fudan University. The median age of the patients was 65 (range, 34-85) years. Before systemic or local antitumor therapy, tumor specific mutations in tumor tissue, pleural effusion supernatant, pleural effusion sediment, and plasma samples from these patients were examined using targeted next-generation sequencing, and TMB levels were calculated respectively. Subgroup analysis was based on smoking history and driver mutation status. Statistical differences were determined using SPSS 16.0 software, and individual groups were compared using the one-way analysis of variance (ANOVA) and LSD-t test. Results: The median TMB level of pleural effusion supernatant was 6.23 mutations/Mb, similar to that of tumor tissue (6.23 vs 6.86 mutations/Mb, t=1.174, P=0.245), but significantly higher than that of pleural effusion sediment (2.49 mutations/Mb, t=3.044, P=0.003) and plasma (2.49 mutations/Mb, t=2.464, P=0.016). Compared with tumor tissue in TMB assessment, pleural effusion supernatant had a positive percentage agreement of 52% (9/17), and a negative percentage agreement of 65% (11/17). Subgroup analysis showed that the TMB level was higher in smokers (n=11) than that in non-smokers (n=23, 14.4 vs 5.4 mutations/Mb, t=3.238, P=0.003). Conclusion: For advanced lung cancer patients with pleural effusion, pleural effusion supernatant is a promising substitute to tumor tissue for TMB assessment, which is a potential biomarker for immunotherapy.
目的： 探讨晚期肺癌患者胸腔积液上清液中肿瘤游离DNA检测肿瘤突变负荷（TMB）的可行性。 方法： 纳入2016年12月至2018年8月复旦大学附属中山医院合并有胸腔积液的晚期肺癌患者34例，男19例，女15例，年龄34~85岁，中位年龄为65岁。在接受全身或局部抗肿瘤治疗之前，采集肿瘤组织、胸腔积液和血标本，用二代靶向测序技术检测肿瘤组织、胸腔积液上清液、胸腔积液沉淀物、血浆标本中肿瘤DNA突变情况，计算TMB水平，并将所有患者按是否有吸烟史、驱动基因突变情况进行亚组分析。采用SPSS 16.0软件对结果进行处理，组间比较采用单因素方差分析（ANOVA）及LSD-t检验。 结果： 胸腔积液上清液中TMB的中位水平为6.23突变/Mb，与肿瘤组织的中位TMB水平（6.86突变/Mb）相似（t=1.174，P=0.245），显著高于胸腔积液沉淀物（2.49突变/Mb，t=3.044，P=0.003）和血浆（2.49突变/Mb）的中位TMB水平（t=2.464，P=0.016）。胸腔积液上清液用于评估TMB与肿瘤组织的阳性一致性为52%（9/17），阴性一致性为65%（11/17）。亚组分析结果显示，吸烟患者（11例）肿瘤组织中TMB水平（14.4突变/Mb）高于不吸烟患者（23例，5.4突变/Mb），差异有统计学意义（t=3.238，P=0.003）。 结论： 对于合并胸腔积液的晚期肺癌患者，检测胸腔积液上清液中TMB水平，有望替代肿瘤组织，作为预测免疫治疗疗效的一种生物标志物。.
Keywords: Lung neoplasms; Pleural effusion; Tumor mutational burden.