Proton Versus Photon Radiotherapy for Nasopharyngeal Carcinoma

Inclusion Criteria: * Pathologically confirmed Nasopharyngeal carcinoma(WHO II/III type). * Age ≥ 18 and ≤ 70 years of age. * Eastern Cooperative Oncology Group score: 0-1. * Adequate laboratory values within 30 dyas of enrollment to study defined as follows: 1) neutrophil \> 2000/mm\^3; 2) platelet \> 100,000/mm\^3; 3) total bilirubin \< 1.5mg/dl; 4) alanine aminotransferase/aspartate aminotransferase \< 1.5 upper limit of normal; 5) SCr \< 1.5mg/dl; creatinine clearance rate \> 60ml/min. * Willing to accept adequate contraception for women with childbearing potential. * Willing to sign the written informed consent; Informed consent must be signed before the enrollment in the trial. Exclusion Criteria: * Presence of distant metastasis. * Received radiotherapy for head and neck before. * Received surgery(except for biopsy) for primary lesion or cervical lymph node. * Previous history of malignant tumor (within 5 years) or simultaneous existence of multiple primary tumors. * Presence of diseases (such as Sjögren syndrome) that may interfere evaluation of xerostomia. * Accompanied with severe major organ dysfunction. * Presence of mental disease that may influence the understanding of informed consent.