Researchers at MD Anderson Cancer Center found traces of bacteria inside both gliomas and brain metastases, revealing a bacterial presence within brain tumors in a Nature Medicine study.

The bacterial components were biologically active and linked to distinct tumor behaviors, including antimicrobial and immune-metabolic pathways, which could influence tumor growth and responses to treatment.

In broader terms, survival outcomes correlated with tumor microbiome composition, with richer bacterial communities associated with shorter survival and specific taxa linked to worse prognosis.

Bacterial composition in brain metastases varied by brain region, with posterior tumors showing more bacteria and greater diversity than anterior ones, potentially due to regional blood supply or metabolism differences.

Researchers note the study is correlational and cannot prove causality; further validation in larger, diverse populations and across environments is needed.

Patient survival tied to tumor microbiome: individuals who survived less than a year tended to have richer bacterial communities, while those living beyond two years had less rich communities; certain bacteria like Paracoccus were more common in poorer survivors.

There were suggested connections between intra-tumoral bacterial elements and bodily microbial communities, particularly the oral microbiome.

In glioblastomas, evidence points to a symbiosis with phosphorus-producing bacteria, possibly helping tumors cope with phosphorus deficiency.

Experiments exposing brain tumor cells to secretions from 30 identified bacteria showed that some bacterial products can alter chemotherapy efficacy, notably Bacillus secretions reducing sensitivity to temozolomide.