Microbiome-directed therapies in oncology: from animal models to clinical implementation

The gut microbiota is increasingly recognized as a key regulator of cancer development, antitumor immunity, treatment response, and therapy-related toxicity. Microbial dysbiosis contributes to chronic inflammation, impaired intestinal barrier function, and immune dysregulation, thereby influencing oncological outcomes. This review summarizes current evidence on probiotics and microbiome-directed interventions in oncology, from mechanistic studies to emerging clinical applications. We discuss interactions among the gut microbiota, microbial metabolites, the immune system, and the tumor microenvironment, highlighting pathways that may affect carcinogenesis, treatment efficacy, and adverse events. Particular attention is given to the role of probiotics in maintaining barrier integrity, modulating immune responses, and reducing gastrointestinal toxicity. While preclinical studies suggest that selected probiotics can enhance antitumor immunity and treatment responses, clinical evidence primarily supports benefits in reducing gastrointestinal complications and improving quality of life. Microbiome modulation represents a promising adjunctive strategy in precision oncology.