Exploring the role of the oral microbiome in saliva, sputum, bronchoalveolar fluid, and tissue tumor in lung cancer: A systematic review.

e20547 Background: To explore the association between the oral microbiome and the presence or progression of lung cancer (LC) using metagenomic sequencing techniques. Methods: Databases, including PubMed and EMBASE, were reviewed from January 2015 to July 2024. Eligible studies included the study of oral microorganisms via genomic sequencing and molecular mechanisms associated with LC in saliva, sputum, bronchoalveolar lavage fluid (BALF), or tumor tissue from LC patients. A quality analysis of the studies was carried out using the New Castell scale (NCS), and a qualitative synthesis was performed according to the localization and sample type. Results: Of the 1,880 scrutinized articles, 50 studies comprised 29 cross-sectional, 7 case-controls, and 14 cohorts were selected. The quality analysis sheds light on potential biases.The findings unveiled a conspicuous overgrowth of specific microbial taxa in LC patients' saliva BALF samples of Veillonella and Streptococcus . However, Veillonella was associated with a better response to ICIs therapy.Conversely, samples from the Bacteroides genus, related to periodontal disease, exhibited no significant correlation with LC. Although oral microorganisms in the tumor tissue were variable, this presence was associated with poor prognosis in LC. However, Prevotella nigrescens were associated with longer PFS. Fusobacterium nucleatum had a poor response in ICs. Oral microorganisms were related to xenobiotics biodegradation, amino acid, sugar, sucrose metabolism, proinflammatory environment, and inhibiting the immune response and cell redox homeostasis. Conclusions: Overgrowth of some oral microorganisms in the saliva and BALF is associated with diagnosis, poor prognosis, and low response to immunotherapy. Further, well-designed studies should evaluate the impact of the oral microbiome on the response to ICs.