Fusobacterium in the microbiome: from health to disease across the oral–gut axis and beyond

Fusobacterium functions as both commensal and pathogen, linking the oral-gut axis to diverse diseases, including cancer. Evidence shows it modulates microbial balance, promotes dysbiosis, and contributes to carcinogenesis by driving inflammation, proliferation, invasion, and immune evasion. This review integrates ecological, molecular, and clinical insights, highlighting its roles in oral and systemic disease and discussing therapeutic potential, underscoring Fusobacterium's dualistic nature and implications for microbiome-targeted interventions.