Pelvic radiotherapy is a common part of treatment used in gynecologic malignancies. The side effects associated with treatment, such as gastrointestinal toxicity, can be acute and chronic. Previous studies have provided little clarity in regard to the best dietary intervention for management of symptoms.
The aim of this systematic review was to summarize the evidence on the efficacy of nutrition interventions involving fiber modification in patients with gynecologic cancers undergoing pelvic radiotherapy to prevent or alleviate gastrointestinal side effects, in comparison to standard care, placebo, or no intervention.
Studies, inclusive of any language and date, up to December 1, 2019, were selected from eight electronic databases: PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, Scopus, Science direct, Clinical Key, Web of Science, and Cochrane. Key study outcomes included gastrointestinal toxicity such as diarrhea/bowel changes, abdominal pain or bloating, and nausea; nutritional status; and quality of life. All studies underwent a quality appraisal using the Academy of Nutrition and Dietetics Quality Criteria Checklist and certainty of evidence was assessed via the Grading of Recommendations Assessment, Development, and Evaluation criteria.
Four studies were included (total number of participants = 89), with quality ratings of neutral or negative. Due to the risk of bias, inconsistency, indirectness, and imprecision, there was very low certainty of evidence that dietary fiber modifications improved these outcomes. Some positive trends regarding improvements in incidence and severity of diarrhea and bowel symptoms were reported; however, the body of evidence was insufficient to form specific recommendations for clinical practice. This is reflected in the Grading of Recommendations Assessment, Development, and Evaluation criteria rating (very low level of certainty) for quality of life and gastrointestinal toxicity outcomes.
This systematic review suggests that supplementary fiber modification during radiation therapy may have some potential benefits with improving gastrointestinal symptoms; however, more definitive evidence and further exploration of fiber in a therapeutic role is required to inform dietary practice.

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