Several studies have also investigated the role of gastro- intestinal microbiota and intestinal mucosa and their effects on the occurrence of oral mucosa [42]. The intestinal micro- biota is effective in the pathogenesis of OM, especially in the recovery phase, by modulating pro-infammatory pathways [43]. There is also evidence linking the role of the gut microbiome in the pathogenesis of OM by regulating immune responses. In addition, bowel dysfunction due to cancer treatment and changes in the gut microbiome can exacerbate the severity of OM [44]