Protective Roles of <i>Bacillus licheniformis</i> Preparation Against Gastrointestinal Dysfunction and Inflammation After Radiotherapy in Children With Medulloblastoma

<b>Aims/Background</b> Probiotics, including <i>Bacillus licheniformis</i>, have been shown to mitigate intestinal inflammation and mucositis by modulating gut microbiota and immune responses; however, their role in radiation-induced gastrointestinal (GI) injury remains unclear. This study aims to investigate the effects of <i>Bacillus licheniformis</i> supplementation on radiotherapy-induced GI dysfunction, inflammation, and survival rates in pediatric patients with medulloblastoma. <b>Methods</b> A total of 205 pediatric patients with medulloblastoma admitted to Jinhua Municipal Central Hospital between March 2015 and March 2020 were divided into an experimental group and a control group based on treatment protocols. All patients received craniospinal irradiation (CSI). Patients in the experimental group received an oral <i>Bacillus licheniformis</i> preparation (one capsule, three times daily) starting one day before CSI and continuing through the completion of radiotherapy, while the control group did not receive the probiotic. Post-radiotherapy adverse reactions were recorded. Serum levels of endothelin (ET), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6) were measured one day before the first radiotherapy session and one day after the final session. A five-year follow-up was conducted to assess patients' survival rates. <b>Results</b> Most of the pediatric medulloblastoma patients developed varying degrees of gastrointestinal symptoms after CSI, with fewer cases observed in the experimental group compared to the control group (all <i>p</i> < 0.05). Serum levels of ET, CRP, TNF-α, IL-1β, and IL-6 significantly increased post-radiotherapy in both groups, but the rise was markedly attenuated in the experimental group (all <i>p</i> < 0.001). However, no significant differences were found in 5-year progression-free survival (hazard ratio [HR] = 1.060, log rank <i>p</i> = 0.716) or overall survival (HR = 1.275, log rank <i>p</i> = 0.350) rates between the two groups. <b>Conclusion</b> <i>Bacillus licheniformis</i> preparation effectively alleviates CSI-induced gastrointestinal dysfunction and inflammation in pediatric patients with medulloblastoma, but does not significantly improve their survival rates.