[The study of pleural effusion supernatant cell-free tumor DNA in tumor mutational burden assessment of advanced lung cancer].

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.

[Detection of epidermal growth factor receptor mutations using bronchial washing fluid in lung cancer patients with negative results by rapid on-site evaluation].

Objective: To evaluate the clinical application of bronchial washing fluid (BWF) in the detection of epidermal growth factor receptor (EGFR) gene mutation in lung cancer patients during diagnostic bronchoscopic procedure. Methods: Patients with suspected lung cancer lesions but failed to be identified as malignancy by rapid on-site cytologic evaluation (ROSE) were enrolled. Performed blocker PCR for EGFR mutation detection using the supernatant and cell pellet of BWF samples and compared the detective results to the EGFR mutation status detected using histologic tumor samples. Results: A total of 85 BWF and paired histological samples were collected at Fudan University Affiliated Zhongshan Hospital from October 2016 to June 2017. There were 46 male and 39 female, with a mean age of 61 years (range 30-87 years). Thirty-one patients had benign diseases and 54 patients had primary lung cancer. Among these 54 lung cancer patients, the diagnoses were made basing on bronchoscopic biopsy samples in 31 patients. The detection rate of EGFR gene mutation in BWF samples was 100.0% concordant with that using histological samples.Another 23 cases whose bronchoscopic biopsy failed to establish malignant diagnoses were further identified by other sampling methods including surgical resection, lung biopsy, etc. A total of 15 patients were identified as EGFR mutated type by pathologic detection or clinically effect assessment, and BWF could detect 11 of them, accounting for 11/15 of all cases. Overall, BWF had achieved an overall accuracy of 95.3% (81/85) comparing to paired tumor histologic samples. Conclusions: BWF is an effective complementary specimen to bronchoscopic biopsy samples in EGFR gene mutation detection in patients with suspected lung cancer lesion and negative biopsy results evaluated by ROSE during bronchoscopy.