IMRT Alone for Stage IB Nasopharyngeal Carcinoma Without High-Risk Features

Inclusion Criteria: 1\. Histopathologically confirmed, newly diagnosed nasopharyngeal carcinoma 3. Age 18-70 years 4. Stage IB disease (T1-2N1M0) per the 9th edition AJCC/UICC staging system 5. Upper-neck nodal metastasis only: inferior border of every positive node at or above the inferior border of the hyoid bone 6. ECOG performance status 0-2 7. Adequate bone-marrow function Exclusion Criteria: 1. Age \> 70 years or \< 18 years 2. Matted lymph nodes: two or more contiguous nodes with loss of intervening fat planes and/or extracapsular extension forming a confluent mass 3. Largest metastatic lymph-node ≥ 3 cm in the longest dimension 4. Lower-neck nodal metastasis: inferior border of any positive node below the inferior border of the hyoid bone 5. Prior malignancy except adequately treated basal-cell or squamous-cell carcinoma of the skin or carcinoma in situ of the cervix 6. Pregnancy or lactation (serum pregnancy test required for women of child-bearing potential; effective contraception mandatory during treatment) 7. Previous radiotherapy to the head-and-neck region 8. Prior chemotherapy or surgery for the primary tumour or metastatic nodes (diagnostic procedures excluded) 9. Any severe comorbidity that would confer unacceptable risk or compromise protocol adherence, including but not limited to unstable cardiac disease, renal failure, chronic hepatitis, or uncontrolled psychiatric disorder 10. History of severe hypersensitivity reactions