Polymorphic microbes: a new emerging hallmark of cancer.

Recognition of the microbiome (and 'polymorphic microbes' within them) as a new emerging hallmark of cancer reflects a wide body of rapidly evolving research. Microbes may be directly carcinogenic, impact host immune responses to promote malignancy, and may be key effectors in determining the efficacy of anticancer therapy. Manipulation of the microbiome is showing promise as an opportunity to influence cancer outcomes.