S. Cai1, Y. Yang2, Y. Tian3, and R. Zhu4; 1Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, SuZhou, China, 2Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China, 3Institute of Radiotherapy & Oncology, Soochow University, Suzhou, China, 4Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Suzhou, China
Purpose/Objective(s): Acute radiation-induced intestinal injury (ARIII) is a common side effect of abdominal and pelvic radiotherapy, which can have negative effects on the prognosis and quality of life of cancer patients. This study aimed to evaluate the potential of supplementing Bifidobacterium longum BL21 (referred to as BL21) in preventing ARIII, and its influence on the compositions of intestinal microbiota and metabolites. Materials/
Methods: Acute radiation-induced intestinal injury (ARIII) is a common side effect of abdominal and pelvic radiotherapy, which can have negative effects on the prognosis and quality of life of cancer patients. This study aimed to evaluate the potential of supplementing Bifidobacterium longum BL21 (referred to as BL21) in preventing ARIII, and its influence on the compositions of intestinal microbiota and metabolites. Results: From April 7, 2023, to October 31, 2023, a total of 44 patients were enrolled. The overall incidence of ARIII was 84.1%, with only 27.2% experiencing grade =2 ARIII, significantly lower than the reported 65% in historical control groups. No adverse events related to BL21 were reported in any patients. Regarding intestinal microbiota, the a-diversity of intestinal microbiota significantly decreased after radiotherapy and was associated with the severity of ARIII. The abundance of Lachnospiraceae significantly increased after radiotherapy (P=0.025). In patients with grade 0/1 ARIII, certain metabolites showed significant upregulation in stool samples at the end of radiotherapy. These included Indole-3-carboxylic acid (P=0.025), alanine (P=0.025), homocysteine (P=0.021), valine (P=0.0028), and phenylalanine (P=0.039). However, this difference was not observed in patients who developed = grade 2 ARIII. Indole-3-carboxylic acid is a key intermediate product in the tryptophan metabolism pathway, while the others are precursor substances in the fatty acid metabolism pathway. Conclusion: Prophylactic use of BL21 can prevent grade =2 ARIII, making it a safe, simple, and effective method in clinical practice. The potential mechanism of the preventive effect of BL21 may involve restructuring the intestinal flora to enhance beneficial bacteria and suppress harmful bacteria. Additionally, it may upregulate the tryptophan metabolic pathway and stimulate the production of short-chain fatty acids.
