Dose-dependent effects of radiotherapy on body composition, nutritional status, and clinical symptoms in head and neck cancer.

Radiotherapy (RT) and chemoradiotherapy (CRT) for head and neck cancer (HNC) frequently result in significant malnutrition, muscle wasting, and systemic inflammation, which can compromise treatment tolerance and clinical outcomes. This study aimed to evaluate the dose-volume effects of RT, symptom burden, and treatment modality on nutritional status, body composition, and inflammatory markers in HNC patients. Eighty-five patients with HNC undergoing adjuvant or definitive RT/CRT were prospectively evaluated at baseline, at the end of treatment, and 6-12 weeks post-treatment. Nutritional status was assessed using the Patient-Generated Subjective Global Assessment (PG-SGA), anthropometric measurements, bioelectrical impedance analysis (BIA), handgrip strength, and laboratory parameters (albumin, prealbumin, transferrin, CRP, hemoglobin, and lymphocytes). Receiver operating characteristic (ROC) analyses were performed to identify RT dose-volume thresholds associated with clinically significant weight and muscle loss. The prevalence of malnutrition increased from 33.3% at baseline to 65.3% at the end of treatment and remained high at 55.6% during follow-up. 42% of patients experienced ≥ 4.6% weight loss, and 49% had ≥ 4.8% muscle mass loss. Higher RT doses (> 65 Gy), larger high-dose volumes (> 48 cc), and greater symptom burden were significantly associated with clinically relevant deterioration in body composition. Patients requiring nutritional support showed greater weight and muscle loss; however, this likely reflects confounding by indication, as these patients had more advanced disease and higher baseline symptom burden. CRP levels increased significantly during treatment, while hemoglobin and lymphocyte counts decreased. RT for head and neck cancer causes substantial and persistent deterioration in nutritional status, muscle mass, and inflammatory markers. RT dose-volume parameters and symptom burden are important predictors of nutritional decline. Early, individualized nutritional intervention combined with effective symptom management is essential to improve treatment outcomes.