Crossover, pilot study of the effect of nutritional intervention with elemental diet on digestive symptom and nutritional status during concurrent chemoradiotherapy for head and neck cancer

INTERVENTION: Elemental diet (300kcal/day) administration in first course of chemoradiotherapy, and no administration in second course No administration of elemental diet in first course of chemoradiotherapy, and elemental diet administration (300kcal/day) in second course CONDITION: Head and neck cancer PRIMARY OUTCOME: Change of nutritional status during chemoradiotherapy, serum albumin SECONDARY OUTCOME: 1)Physical examination, blood biochemistries ; 2)Adverse events INCLUSION CRITERIA: 1.Patients with head and neck cancer who will undergo radiotherapy. 2.Patient age at the time of obtaining informed consent is 20 years of age or older. 3.Written informed consent.