Comparison of Sputum and Oropharyngeal Microbiome Compositions in Patients with Non-Small Cell Lung Cancer

Abstract

Recent findings indicate that the microbiota is involved in the development of lung cancer by inducing inflammatory responses and generating genome damage. This study aimed to compare sputum microbiomes from the mouth and oropharynx in non-small cell lung carcinoma (NSCLC) patients. A second goal was to search for bacterial taxonomic units that behave differently in the microbiome of NSCLC patients and healthy subjects. In the study, the taxonomic composition of the sputum and oropharyngeal microbiomes of 23 male patients with untreated NSCLC and 20 healthy subjects were compared. Next-generation sequencing of bacterial 16S rRNA genes was used to determine the taxonomic composition of the respiratory microbiome. Using the Kruskal-Wallis test, increased alpha diversity was observed in the sputum microbiome compared to that of the oropharynx, but this was evident only in NSCLC patients and not in healthy subjects. Using the Robust Aitchison PCA test, differences in beta diversity were found between sputum and oropharynx samples, and these differences were significant both for NSCLC patients (p = 0.045) and healthy controls (p = 0.009). However, no significant statistical differences were detected using the Robust Aitchison PCA when only comparing oropharyngeal samples from NSCLC patients and controls, nor when comparing sputum samples alone. Analysis of differences in the relative percentage of individual bacterial taxa using the Mann-Whitney U-test, and taking into account the FDR correction, showed an increase in the genus <em>Rothia</em> in oropharyngeal samples of NSCLC patients, as compared to control subjects (4.98 ± 6.33 vs 2.21 ± 6.28; p = 0.0008). However, linear discriminant analysis using LefSe did not show <em>Rothia</em> as a differentially regulated feature between NSCLC and controls in the oropharynx. Thus, more research is needed to identify possible bacterial NSCLC biomarkers in the oropharynx.