Abstract: Objective: To observe the change of skeletal muscle mass in patients with Head and Neck Cancer during radiotherapy and analyze its influencing factors. Methods: Patients with Head and Neck Cancer treated with radiotherapy in a cancer hospital in Beijing from March 2017 to September 2019 were recruited. The symptom section of Patient Generated Subjective Global Assessment (PG-SGA) was used to assess the Nutrition Impact Symptoms (NIS) of patients before (T1), during (T2) and at the end (T3) of the radiotherapy. Dietary intake was recorded by 24-hour dietary recall and skeletal muscle mass were measured by bioelectrical impedance analysis. Generalized Estimating Equations (GEE) were used to analyze the influencing factors of skeletal muscle mass of head and neck cancer patients during radiotherapy. Results: Totally 459 patients were completely investigated. At the three evaluation time points, the skeletal muscle mass was (26.31±5.08) kg, (25.60±4.83) kg, (24.62±4.68) kg respectively; the incidence of NIS was 38.1% (175/459), 93.2% (428/459), 95.4% (438/459) respectively; standard daily energy intake (stDEI) was (24.94±8.51) kcal/(kg·day), (20.47±9.14) kcal/(kg·day), (18.23±9.75) kcal/(kg·day) respectively, and standard daily protein intake (stDPI) was (0.98±0.39) g/(kg·day), (0.86±0.39) g/(kg·day), (0.84±0.51) g/(kg·day) respectively. With the progress of radiotherapy, the patient's skeletal muscle mass gradually decreased, NIS increased, and energy and protein intake declined. Changes in skeletal muscle mass of patients were closely related to whether they had undergone surgery before radiotherapy, dietary energy intake and NIS scores. Conclusion: Patients with radiation therapy have reduced skeletal muscle mass after treatment, and patients with non-surgical, insufficient dietary energy intake and NIS have a greater reduction in skeletal muscle mass. It is suggested that attention should be paid more to non-surgical patients, and nutrition-related symptoms management and dietary intervention should be strengthened to reduce the loss of skeletal muscle mass.

Key words: Head and Neck Cancer; radio therapy; nutrition impact symptoms; dietary intake; skeletal muscle