The role of nutritional status and sarcopenia in treatment tolerance and toxicity in head and neck cancer: a narrative review.

INTRODUCTION: Malnutrition, sarcopenia, and adverse body-composition phenotypes are highly prevalent in patients with head and neck cancer (HNC) and have been increasingly recognized as clinically relevant predictors of treatment tolerance, treatment-related toxicity, and oncologic outcomes. Morphofunctional assessment has emerged as a comprehensive approach for evaluating nutritional and functional status beyond conventional anthropometric measures. METHODS: A narrative review was conducted using a structured literature search in PubMed/MEDLINE, Scopus, and Web of Science from database inception to June 2026. Studies evaluating the relationship between nutritional status, sarcopenia, body composition, treatment tolerance, treatment-related toxicity, functional outcomes, and prognosis in adult patients with HNC were considered. Clinical practice guidelines, systematic reviews, meta-analyses, and original studies published in English or Spanish were included. RESULTS: Current evidence demonstrates that malnutrition, sarcopenia, and low skeletal muscle mass are consistently associated with increased treatment-related toxicity, poorer treatment tolerance, prolonged hospitalization, higher postoperative complication rates, and reduced survival. Body-composition assessment, particularly through computed tomography-based analysis, provides clinically relevant prognostic information beyond conventional anthropometric parameters. Emerging evidence also supports the role of morphofunctional assessment, including muscle strength, physical performance, and muscle ultrasound, for identifying patients at nutritional risk and improving risk stratification. In parallel, multimodal supportive-care strategies integrating nutritional intervention, exercise, and prehabilitation have shown potential to preserve functional status and improve treatment preparedness. CONCLUSION: Malnutrition, sarcopenia, and adverse body-composition phenotypes represent important predictors of clinical outcomes in patients with HNC. The incorporation of morphofunctional assessment into routine clinical practice may facilitate earlier identification of vulnerable patients and support more individualized nutritional and rehabilitative interventions. Future research should prioritize longitudinal morphofunctional assessment, standardization of assessment methods, and the integration of personalized supportive-care strategies throughout the oncologic trajectory.