Nutrition Recommendations for People Living After Cancer: A Systematic Review and Critical Appraisal of Clinical Practice Guidelines

Background/Objectives: Clinical practice guidelines are essential tools for ensuring evidence-based, standardised care for people living after cancer; however, the quality of international clinical practice guidelines with nutrition recommendations for this population has not been assessed. This systematic review aimed to critically appraise the quality of international clinical practice guidelines for the nutritional care of people living after cancer and to summarise common recommendations for both the overall condition and for breast, colorectal, prostate, and head and neck cancers. Methods: Guidelines providing recommendations for nutritional management in people living after cancer were comprehensively searched in five electronic databases (PubMed, Web of Science Core Collection, CINAHL, SCOPUS, and Google Search). Included guidelines were appraised using the AGREE II and AGREE-REX tools. Results: Twenty-two clinical practice guidelines met the inclusion criteria. From the AGREE tools, ten guidelines were rated as "recommended", eight guidelines as "recommended with modifications", and four guidelines as "not recommended". The AGREE II domains with the highest mean percentages were Editorial Independence (81%, range = 46-100%), Clarity of Presentation (80%, range = 58-94%), and Scope and Purpose (79%, range = 42-100%); the domain with the lowest mean percentage was Applicability (39%, range = 6-77%). The AGREE-REX item with the highest mean percentage was Evidence (72%, range = 25-100%), while the items with the lowest mean percentage were Values and Preferences of Patients/Populations (25%, range = 0-75%) and Values and Preferences of Policy/Decision-Makers (25%, range = 0-83%). The most common nutrition recommendations provided were weight management; increased consumption of fruits, vegetables, and wholegrains; strategies for symptom management; and limitation of specific carcinogenic foods. Twelve clinical practice guidelines provided specific recommendations for living after different cancer types, with the most commonly considered types being head and neck cancer, breast cancer, colorectal cancer, and prostate cancer. Conclusions: While many guidelines were rated highly for clarity and Editorial Independence, most were limited in practical applicability and in their consideration of patient and policymaker values. The findings underline the necessity for more robust, comprehensive, and patient-centred guideline development to support consistent, evidence-based nutritional recommendations for people living after cancer worldwide.