Concurrent Chemotherapy for the Intermediate Risk Nasopharyngeal Carcinoma In Intensity-modulated Radiotherapy Era

Inclusion Criteria: * Patients with newly histologically confirmed non-keratinizing (according to WHO histologically type. * Tumor staged as T1-2N1/T2-3N0(according to the 7th AJCC edition). * No evidence of distant metastasis (M0). * Satisfactory performance status: Karnofsky scale (KPS) ≥ 70. * Adequate marrow: leucocyte count ≥ 4000/μL, hemoglobin ≥ 120g/L for male, ≥ 120g/L for female , and platelet count ≥ 100000/μL. * Normal liver function test: Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST) \< 1.5×upper limit of normal (ULN) concomitant with alkaline phosphatase (ALP) ≤ 2.5×ULN, and bilirubin ≤ ULN. * Adequate renal function: creatinine clearance ≥ 60 ml/min. * Patients must be informed of the investigational nature of this study and give written informed consent. Exclusion Criteria: * Neck lymph node with extracapsular spread. Maximal axial diameter of neck lymph node ≥30mm, positive neck lymph node at level IV and/or Vb. * Pretreatment plasma EBV DNA level ≥4000 copy/ml. * WHO Type keratinizing squamous cell carcinoma or basaloid squamous cell carcinoma. * Age \> 65 or \< 18. * Treatment with palliative intent. * Prior malignancy except adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer. * Pregnancy or lactation (consider pregnancy test in women of child-bearing age and emphasize effective contraception during the treatment period). * History of previous RT (except for non-melanomatous skin cancers outside intende…