Comparative analysis of the mutation detection using malignant pleural effusion and blood cell-free DNA samples in lung cancer.

Abstract

e20518 Background: Malignant pleural effusion (MPE) is an abnormal amount of fluid to collect between the chest wall and the lung, and it denotes an advanced malignant disease process. MPE presents a severe medical condition which can result in breathlessness, pain, cachexia and reduced physical activity. MPE is considered to bear cancer signatures because it contains tumor cells released from malignancies, thus can be applied in high-throughput sequencing for cancer screening. Cell-free DNA (cfDNA) in blood consists of small fragments released from apoptotic cells or cancer cells, and pathological conditions can influence this process. Therefore, detection of cfDNA in peripheral blood can identify abnormalities of individuals in a noninvasive manner. Here, we wonder the difference of MPE and cfDNA in lung cancer-related mutation detection. Methods: In this study, MPE and blood samples from 216 patients with late-stage lung cancer were collected and applied to library construction and next-generation sequencing. All samples were collected during August 2018 to December 2022. We focused on the key mutations in cancer-causing genes and drug treatment-related genes (e.g., EGFR, KRAS, BRAF, ERBB2, etc.). Statistical analysis was conducted to compare the detection results between MPE and cfDNA samples by Fisher’s exact test. Results: Among the 216 patients, 60 patients (60/216 = 27.8%) were identified as negative detection with no mutation detected in cancer-causing genes in MPE and blood samples. Of the remaining 156 pairs of samples, there were 118 (118/216 = 54.6%) pairs showing the positive detection in both MPE and blood samples. 12 patients (12/216 = 5.6%) demonstrated the positive detection in blood samples while negative detection in MPE samples. The other 26 patients (26/216 = 12%) demonstrated the positive detection in MPE but negative detection in blood samples. There is no significant difference in detection rates between two types of samples (p = 0.194). Similarity, we next focused on the mutations in drug treatment-related genes and identified 91 patients (91/216 = 42.1%) as negative detection. There were 85 patients (85/216 = 39.4%) showing the same positive detection both in MPE and blood samples. 13 patients (13/216 = 6%) demonstrated the positive detection in blood samples but negative detection in MPE samples. The other 27 patients (27/216 = 12.5%) demonstrated the positive detection in MPE but negative detection in blood samples. No significant difference in detection rates was observed between two types of samples (p = 0.211). Conclusions: The mutation detection results in MPE and blood samples turned out to be consistent in most conditions, suggesting an alternative application of MPE or blood samples in cancer screening. Nonetheless, it is still valuable to integrate the information in both MPE and blood samples for a higher detection sensitivity.