Intertumoral microbiome of brain metastases and glioblastoma

Brain tumors, including glioblastoma multiforme (GBM) and brain metastases, present a significant clinical challenge. Recent research highlights the presence of intra-tumor bacteria across many tumor types, and yet, the microbiome of brain tumors remains largely underexplored. Here we employed diverse visualization techniques, culturomics, and 16S rRNA sequencing to characterize the microbiome of 322 brain tumors. Our findings show that brain metastases exhibit higher bacterial richness and diversity and a unique taxonomic composition as compared to GBM. We also detected a higher richness and diversity of brain metastases that are located in posterior vs. anterior brain regions. Functional analysis revealed enrichment of bacterial metabolic pathways associated with tumor spread and metastasis in brain metastases and with alternative phosphorus utilization in GBM. Overall, these findings shed new insights into the microbiome of brain tumors, highlighting variations by type and location, and emphasizing the need for further research into their biological effects.