Early Nutritional Intervention in NPC Patients Undergoing Concurrent Chemoradiotherapy

Inclusion Criteria: * Pathologically confirmed nasopharyngeal carcinoma (NPC). * The clinical stage of NPC is T1-4 N1-3 M0 (AJCC 7th edition). * Planned to receive concurrent chemoradiotherapy with intensity-modulated radiation therapy (IMRT). * Age ≥ 18 years and \< 75 years. * Performance status (PS) score 0-1. * NRS2002\<3 . * Blood regular test should be satisfied the following conditions: white blood cell count ≥3.5×109/L， Neutrophil count ≥1.5×109/L，platelet count ≥100×109/L，hemoglobin ≥10g/L * Liver and kidney functions test should be satisfied the following conditions: aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) \< 2.5 times the upper limit of normal value, bilirubin \< 1.2 times the upper limit of normal value, creatinine \< 1.2 times the upper limit of normal value, and alkaline phosphatase \< 5 times the upper limit of normal value. * Could complete required oral nutrition, questionnaire survey and follow-up. * Signed informed consent voluntarily. Exclusion Criteria: * Had a history of head and neck radiotherapy. * Known allergic reaction to any component of ONS, or severe allergic constitution. * With any unstable systemic disease (such as uncontrolled infectious diseases, uncontrolled hypertension, uncontrolled metabolic diseases and so on). * Serious cardiovascular diseases in 6 months (such as Congestive heart failure and myocardial infarction). * Pregnancy and lactation. * Other conditions that the investigators consider as inappropriate for enrolling into this study. * Has a history of malignant tumors in 5 years, except for tumors that have been cured only by surgery and with a disease free survival for five years, cured basal cell carcinoma of skin and cured carcinoma in situ of the cervix.