Lung microbiota features of stage III and IV non-small cell lung cancer patients without lung infection

Background: The microbial community affects the occurrence, development, metastasis and treatment response of cancers. But the detailed role and characteristics of lung microbiota (LM) in non-small cell lung cancer (NSCLC) are not fully known. For NSCLC associated microbiota analysis, it is valuable to combine multiple levels of detection, e.g., tumor, blood plasma, and bronchoalveolar fluid (BALF), but not single tissues. Methods: This study collected above three sample types from NSCLC patients free from lung infection and aimed to describe their LM features using sequencing techniques. All patients diagnosed at the Department of Oncology in Shijiazhuang People's Hospital with stage III or IV NSCLC from May 2019 to April 2020 were enrolled. All 37 pieces of tumor tissues and 6 blood samples were sent for pathogen targeted sequencing; for the BALF samples, 4 were used for pathogen targeted sequencing and 2 were sent for 16S ribosomal DNA (rDNA) sequencing. Results: We detected 49 pathogenic microorganisms (PMs) in the 37 tumor samples, 28 PMs in the 4 BALF samples, and 14 PMs in the 6 plasma samples. Overall, there were 5 common PMs in 3 types of samples. Between the tumor and BALF samples, there were another 11 common elements. In the 5 tumor plasma pairs, the presence of a specific PM in blood was not necessarily consistent with that in the tumor. In the tumor-BALF pairs, the PM diversity was dramatically higher in the BALF than in the tumor. The PMs detected in the BALF could largely cover the PMs in the tumor. In the BALF 16S rDNA sequencing, there were 82 common operational taxonomic units (OTUs), and the microbiota in the BALF of advanced NSCLC patients exhibited some similarity. Conclusions: This study showed the unique features of LM. The amount of intra-tumoral PMs was not necessarily consistent with that in the blood, but there was an obvious correlation between the intra-tumoral microbiota and that in the BALF. It is convenient and non-invasive to obtain BALF. Detection of LM classification and abundance in the BALF may help evaluate the severity of NSCLC.