Abstract
The gut microbiota is increasingly recognized as a key determinant of cancer susceptibility, functioning as a dynamic interface between environmental exposures and host physiology. Dysbiosis disrupts immune homeostasis, epithelial integrity, and metabolic equilibrium, thereby fostering a microenvironment conducive to oncogenesis. Conversely, a balanced microbial ecosystem and its metabolites exert potent anti-tumor effects through immune modulation, maintenance of mucosal barrier function, and detoxification of carcinogens. This Review synthesizes emerging mechanistic insights into how commensal microbes and their metabolic products coordinate host defense pathways to suppress malignant transformation. We further discuss translational strategies-ranging from probiotics, prebiotics, and synbiotics to fecal microbiota transplantation and dietary interventions-that leverage microbiome modulation for cancer prevention. Despite compelling preclinical evidence, clinical translation remains constrained by inter-individual variability and incomplete mechanistic understanding. Integration of multi-omics analyses, gnotobiotic models, and precision microbial engineering offers a path toward microbiota-based interventions as a cornerstone of personalized cancer prevention and immunomodulation.