Objective To explore the relationships between swallowing functional outcomes and nutritional status in patients with head and neck cancer undergoing radiotherapy (RT).

Methods This longitudinal study included 122 patients. Data were collected at three time points: baseline (T₁), the third week of RT (T₂) and the completion of RT (T₃). The Common Terminology Criteria for Adverse Events was used to assess the symptom of dysphagia and other toxicities; the MD Anderson Dysphagia Inventory (MDADI) was used to assess the patient-perceived swallowing functional outcomes; the nutritional status was evaluated by the weight ratio and the Patient-Generated Subjective Global Assessment (PG-SGA). The generalised estimating equation (GEE) was used to measure the correlation of MDADI with the weight ratio or PG-SGA and also to analyse the influential factors of swallowing functional outcomes.

Results The participants’ acute dysphagia rates were 5.7% at T₁, 69.7% at T₂ and 77.9% at T₃. The swallowing functional outcomes worsen over RT (p<0.001) and were associated with weight ratio (β=0.032, p=0.008) and PG-SGA (β=−0.115, p<0.001). GEE models showed that patients with cancer of the pharynx region, advanced stage, chemoradiotherapy and high RT dose perceived worse swallowing functional outcomes. Oral mucositis, pharynx mucositis and salivary gland inflammation were positively correlated with swallowing functional outcomes, and the pharynx mucositis presented the highest absolute value of β.

Conclusion The swallowing functional outcomes were negatively correlated with nutritional status. Healthcare professionals should identify early on the population at higher risk and focus on multiple toxicities, especially the management of pharynx mucositis, to improve nutritional status.