Microbiome modulation of tumorigenesis and immune responses

Abstract The microbiome has emerged as a critical, context-dependent regulator of tumorigenesis and anticancer immunity, capable of either promoting cancer progression or protecting against malignancy. This dual role is mediated by multiple interconnected mechanisms—including chronic inflammation, modulation of immune responses, and alterations in host metabolic signaling. These microbiome-cancer interactions vary across organs, influencing malignancies in the colon, breast, lung, and beyond. Clinically, the microbiome significantly affects patient responses to cancer therapies, particularly immunotherapies such as immune checkpoint blockade (ICB) and chimeric antigen receptor (CAR)-T cell therapy. Although emerging therapeutic strategies aimed at modulating the microbiome have shown promising early results, challenges remain, including individual microbiome variability and the dynamic interplay between the immune system and microbial communities. Nevertheless, harnessing the microbiome holds significant potential to transform precision oncology, offering personalized cancer prevention and treatment strategies tailored to each patient’s unique microbial ecosystem.