Preventive effects of combined live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus cereus tablets on radiation pneumonitis-associated with cyberknife treatment for pulmonary malignancies

BACKGROUD: To investigate the preventive effects of combined live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus cereus tablets (CBLEBTL) on patients with radiation pneumonitis associated with CyberKnife treatment for pulmonary malignancies. METHODS: In total, 130 patients who received CyberKnife treatment for pulmonary malignancies at the First Hospital of Hebei Medical University between August 2023 and February 2025 were enrolled. Patients were randomly categorized into the experimental group (n = 65) or control group (n = 65). While both groups received CyberKnife treatment for pulmonary lesions, the experimental group additionally received CBLEBTL (0.5 g/dose, thrice daily). The primary endpoint was to determine the incidence of RP, and secondary endpoints included onset time of RP and Eastern Cooperative Oncology Group performance status (ECOG PS) scores. RESULTS: = 5.340, P = 0.021). The mean onset time of RP was significantly delayed in the experimental group than in the control group (176.9 vs. 166.6 days; hazard ratio = 0.34, 95% confidence interval: 0.15-0.80, P < 0.05). ECOG PS of the experimental group was significantly lower than that of the control group at 2, 4 and 6 months post-CyberKnife treatment (P < 0.05). CONCLUSION: CBLEBTL effectively reduced the incidence of CyberKnife-associated RP among patients with pulmonary malignancies, delayed RP onset, and improved their quality of life. TRIAL REGISTRATION: This prospective trial was registered retrospectively (after patient enrollment began) because of delays in institutional approval processes. The retrospective registration was approved by the Ethics Committee of The First Hospital of Hebei Medical University (Approval No. [2025]074). The trial is registered at: WHO-primary registry ChiCTR (No. ChiCTR2500104615; Date: 19-Jun-2025), accessible via WHO ICTRP ( https://trialsearch.who.int/ ); China's National Public Health Security Information Platform (No. MR-13-25-043029; Date: 09-Jun-2025). All study procedures followed the original protocol without modifications.