Impact of Dietary Fiber Intake on the Immunological Response to Immunotherapy in Cancer Patients: A Scoping Review

INTRODUCTION: Immunotherapy has emerged as a major therapeutic strategy for cancer, and accumulating evidence indicates that the gut microbiota influences its effectiveness, highlighting the potential role of dietary fiber. OBJECTIVE: To evaluate the scientific evidence regarding the relationship between dietary fiber intake, immune modulation, and the response to immunotherapy in patients with cancer. METHODOLOGY: An integrative review was conducted using the MEDLINE, BVS, and EMBASE databases with the descriptors "Neoplasms," "Dietary Fiber," and "Immunomodulation." Original studies involving patients with cancer undergoing immunotherapy that evaluated dietary fiber intake through habitual diet, dietary intervention, or supplementation, as well as its association with immune response, gut microbiota, or clinical outcomes were included. RESULTS: A total of 325 records were identified, of which three studies met the inclusion criteria. DISCUSSION: Higher dietary fiber intake was associated with improved therapeutic responses and favorable changes in the gut microbiota. The included studies involved patients with melanoma receiving immune checkpoint inhibitors, predominantly anti-PD-1 therapy. CONCLUSION: Dietary fiber plays a relevant role in gut microbiota modulation and may enhance the effectiveness of immunotherapy.