Distinct gut microbiota composition in pediatric patients with central nervous system (CNS) tumors: A comparative study

Background Central nervous system (CNS) tumors are the leading cause of cancer-related deaths in children aged 0-14 years. Despite significant efforts, targeted therapies based on identified pathways have not improved survival rates. Research has shown that the gut microbiota (GM) can influence brain tumor cell proliferation, suggesting that the microbiota-gut-brain axis plays a role in CNS cancer. Our study aims to assess whether the GM composition in pediatric CNS tumors exhibits specific characteristics.Methods The study included 18 pediatric patients, 9 diagnosed with CNS tumors (CNS tumors group) and 9 with other tumor types (extra-CNS tumors group). Microbial DNA was extracted from stool samples, and 16S DNA libraries were generated and sequenced. GM composition was analyzed using amplicon sequence variant (ASV) tables.Results Alpha-diversity analysis, represented by the number of observed features, was lower in the CNS tumors group (P = .0054), while Pielou's evenness index was similar between groups. LEfSe analysis revealed a significantly reduced abundance of the Firmicutes phylum in CNS tumors group, along with other taxa within this phylum, such as the Clostridia class, Clostridiales order, and Lachnospiraceae family, compared to extra-CNS tumors group. Further analysis using sPLS-DA showed a distinct pattern in GM composition in the CNS tumors group, with lower levels of several taxa, particularly the Firmicutes phylum, Lachnospiraceae family, Clostridiales order, Clostridia class, Ruminococcaceae and Coriobacteriaceae families, and Blautia genus.Conclusions Pediatric patients with CNS tumors have a distinct GM composition. The reduction of specific beneficial microbial taxa may contribute to tumor growth through the microbiota-gut-brain axis.