Oral microbiome diversity and composition before and after chemotherapy treatment in pediatric oncology patients

Objective This study explored how anticancer treatment affects the oral microbiome in pediatric patients and its link to oral mucositis (OM). It also examined the effects of different mouth rinses (Caphosol vs. saline solution). Materials and Methods Saliva samples were collected from patients before and after chemotherapy in a controlled, double-blind, randomized clinical trial. The trial compared Caphosol and saline solution mouth rinses in patients aged 2 to 17.99 years. Bacterial DNA from saliva samples was analyzed using next-generation sequencing to evaluate 16S rRNA. Results We analyzed 110 saliva samples from pediatric cancer patients before and after treatment, focusing on those with and without OM. Significant differences were found in bacterial taxa, including the Bacteroidota phylum, which was more abundant in patients without lesions before treatment. Cancer treatment increased the abundance of the Proteobacteria phylum. Distinct microbiome profiles were associated with OM development, including increased pathogenic species like Rothia mucilaginosa and Fusobacterium periodonticum . Differences in microbiota composition were also found between patients using Caphosol and saline solution mouth rinses. Conclusions Changes in the oral microbiota before and after anticancer treatment are linked to OM development, offering potential for identifying high-risk patients and promoting protective bacteria. Trial registration: The current trial was registered at Clinical trials.gov (ID: NCT02807337, Date: 20-February-2020).