The functional role of respiratory microbiota has attracted an accumulating attention recently. However, the role of respiratory microbiome in lung
carcinogenesis is mostly unknown. Our study aimed to characterize and compare bilateral lower airway microbiome of
lung cancer patients with unilateral lobar masses and control subjects. Protected bronchial specimen brushing samples were collected from 24
lung cancer patients with unilateral lobar masses (paired samples from cancerous site and the contralateral noncancerous site) and 18 healthy controls undergoing bronchoscopies and further analyzed by
16S rRNA amplicon sequencing. As results, significant decreases in microbial diversity were observed in patients with
lung cancer in comparison to the controls, alpha diversity steadily declined from healthy site to noncancerous to cancerous site. Genus Streptococcus was significantly more abundant in
cancer cases than the controls, while Staphylococcus was more abundant in the controls. The area under the curve of genus Streptococcus used to predict
lung cancer was 0.693 (sensitivity = 87.5%, specificity = 55.6%). The abundance of genus Streptococcus and Neisseria displayed an increasing trend whereas Staphylococcus and Dialister gradually declined from healthy to noncancerous to cancerous site. Collectively,
lung cancer-associated microbiota profile is distinct from that found in healthy controls, and the altered
cancer-associated microbiota is not restricted to
tumor tissue. The genus Streptococcus was abundant in
lung cancer patients and exhibited moderate classification potential. The gradual microbiota profile shift from healthy site to noncancerous to paired cancerous site suggested a change of the microenvironment associated with the development of
lung cancer.