18F-FDG PET/CT Guided Reduced-dose Radiotherapy for Nasopharyngeal Carcinoma

Inclusion Criteria: 1. Pathology confirmed nasopharyngeal squamous cell carcinoma. 2. Stage I-IVA（8thAJCC/UICC staging system). 3. Aged 18-80 years. 4. KPS≥70. 5. Have measurable lesions on 18F-FDG PET/CT before treatment. 6. HGB≥90 g/L，ANC≥1.5×109 /L，PLT≥80×109 /L. 7. ALT,AST\<2.5 fold of ULN；TBIL\<2.0×ULN. 8. CCR≥60ml/min or Cr\<1.5×ULN. 9. Signed informed consent. 10. Have follow up condition. Exclusion Criteria: 1. Past malignancies history (except for stage I non-melanoma skin cancer or cervical carcinoma in situ). 2. Age \<18 or \>80years. 3. Pregnancy or lactation. 4. History of previous radiotherapy (except for non-melanomatous skin cancers outside intended RT treatment volume). 5. Prior chemotherapy or surgery (except diagnostic) to primary tumor or nodes. 6. With sever infection and internal disease. 7. Major organ dysfunction, such as decompensated cardiopulmonary, kidney, liver failure, cannot tolerate surgical treatment.