Role of gut microbiota in cancer modulation: molecular mechanisms and emerging therapeutic strategies

The gut microbiota exerts profound effects on host physiology, immunity, and disease susceptibility, with growing evidence implicating its role in cancer initiation, progression, and therapy response. Dysbiosis and microbial-derived metabolites contribute to oncogenesis by modulating epithelial signalling, immune regulation, and systemic inflammation. This review synthesises current knowledge on the crosstalk between the gut microbiome and cancer, spanning molecular mechanisms, site-specific malignancies, and treatment outcomes. We discuss how microbial pathways, including NF-κB, STAT3, Wnt/β-catenin, and inflammasome activation, shape tumour biology, and how microbiota profiles correlate with cancer risk and progression in colorectal, gastric, liver, breast, gynaecological, and pulmonary cancers. Furthermore, we highlight the microbiome's impact on responses to chemotherapy, radiotherapy, and immunotherapy. Finally, we evaluate therapeutic strategies targeting the microbiota, from conventional dietary and probiotic interventions to cutting-edge approaches such as faecal microbiota transplantation, engineered bacterial strains, and microbiome-based biomarkers. Understanding these complex interactions offers novel opportunities to integrate microbiome science into precision oncology.