Abstract: Radiation pneumonia, as a common and severe complication as well as a dose-limiting factor in radiotherapy for thoracic tumors, has an incidence rate ranging from 10% to 30%. Once RP occurs, it can cause irreversible changes in lung function, resulting in the interruption or cessation of radiotherapy and serious clinical consequences. Currently, there is a lack of effective prevention and treatment methods. A vast number of microbial communities coexist in the human body. Due to the anatomical connection between the oral cavity, lungs, and intestines, and the interconnection between the mucosal immune systems of the intestinal and pulmonary tracts, the oral and intestinal microbiota not only affect the oral cavity and intestines themselves, but also can indirectly affect the course of lung diseases through their own or metabolic products via the bloodstream or directly through body cavity transplantation. Based on the interaction and influence of the oral and intestinal microbiota on lung diseases, this paper proposes the crucial role of the “oral—intestinal—pulmonary axis” in the occurrence and development of RP. By regulating the balance of the oral and intestinal microbiota, this paper offers a new strategy for the clinical prevention and treatment of RP, and simultaneously provides evidence-based medical evidence for strengthening the popularization of scientific knowledge to enhance patients′ awareness of maintaining good oral and intestinal microbiota health.

Key words: radiation pneumonia, oral microbiota, Gut microbiome, oral—gut—lung axis