Gut-brain Axis Roles in Brain Tumors: Pathophysiological Insights and Research Advances

Background and Aim: This study reviewed the association between gut microbiota and primary brain malignancies, with a focus on underlying metabolic and immunologic mechanisms, and possible therapeutic approaches. Methods and Materials/Patients: A literature search was carried out for a narrative review related to the microbial components of the gut-brain axis (GBA) and their potential effects on brain tumors’ formation, growth, and course of treatment with a focus on recent publications. Results: Studies have highlighted likely mechanisms of the crosstalk between the gut and brain through an anatomical and physiological pathway, known as the GBA. Moreover, the metabolites and signaling molecules produced by gut microbiota were found to be involved in maintaining the blood-brain barrier (BBB) integrity and brain homeostasis. In addition, studies have revealed the potential negative effect of gut dysbiosis on tumorigenesis and deleterious inflammatory and immunological cascades within the brain. Pre-clinical and clinical investigations indicated the role of modulation of gut microbiome in brain tumors. Conclusion: Previous investigations on interactions between gut microbiome and central nervous system (CNS) have revealed potential pathways through which interventions on microbiota can regulate brain tumor epigenetics and microenvironment. The findings on modifying microbiota utilizing probiotics, fecal microbial transplantation, and supplemented dietary regimen were promising; nonetheless, further investigation is needed to translate these findings into clinical brain cancer treatment applications.