Symptomatologic outcomes of gut microbiota modifiers (probiotics, prebiotics and synbiotics) in cancer care: A scoping review of randomized controlled trials

Background: Microbiota modifiers offer potential benefits for improving the wide spectrum of symptoms and clinical outcomes in individuals with cancer. However, there is a lack of comprehensive literature mapping to determine which specific cancer and treatment-related symptoms have been investigated as potential targets for gut microbiota modifiers. This scoping review aims to systematically analyze clinical trials on microbiota modifiers in managing cancer and treatment-related symptoms in adults. Methods: We conducted a scoping review of randomized controlled trials (RCTs) across four databases up to May 2025, following our published protocol and JBI principles with PRISMA 2020 guidelines. Results: The literature review identified 33 eligible studies, primarily involving patients with pelvic cancers. The most common outcomes examined in the clinical trials were gastrointestinal symptoms. Other studies focused on patients with head, neck, and breast cancer, examining quality of life, mucositis, fatigue, anxiety, depression, and the use of rescue drugs. Conclusion: Despite evidence of potential benefits for gastrointestinal symptoms, inconsistent findings across studies warrant further well-designed, large-scale research to understand probiotics' effectiveness and mechanisms.