Recent research identifies diverse microbial communities residing within tumors, even in organs far from the gut, that significantly influence cancer progression and treatment outcomes. This commentary establishes a formal definition for the tumor microbiota, encompassing various microorganisms and their metabolites located physically within the tumor environment. The authors emphasize that these microbes can reprogram host cells, affecting hallmarks like metastasis, immune evasion, and drug resistance. To address technical challenges such as low-biomass contamination, the text advocates for orthogonal validation through sequencing, spatial imaging, and culture-based methods. By establishing these rigorous reporting standards, the field aims to move from mere correlation toward causal, clinically actionable insights. Ultimately, understanding these host-microbe interactions may lead to novel diagnostic biomarkers and targeted therapeutic strategies for cancer patients.

References:

• Duan T, Rosenbaum A, Chandra V, et al. Toward a consensus on the tumor microbiota: Evidence, standards, and interpretation[J]. Cancer Cell, 2026.