The gross tumor volumes of the primary site and the neck nodes (GTVnx and GTVnd) could be delineated according to the post-NACT tumor position and receive radical radiation dose, while the tumor disappear after NACT could be encompassed in the first clinical target volume (CTV1) and receive high preventive radiation dose. Through this method,it is more likely to achieve the ultimate goal that maximize the chance of cure while minimize the injury of surrounding normal tissues, maintaining organ function and life quality. Therefore, this stage II clinical trial was designed to study the prognosis and locoregional failure patterns of this target volume delineation method in LA-NPC treated with NACT plus CCRT.

Inclusion Criteria:

1. histologically confirmed NPC;
2. no evidence of distant metastasis;
3. no previous treatment for NPC;
4. stages III-IVb disease according to the staging system of the 6th AJCC/UICC;
5. adequate liver, renal and bone marrow function;
6. Karnofsky Performance Status (KPS) ≥80 scores.

Exclusion Criteria:

1. fine-needle aspiration biopsy, incisional or excisional biopsy of neck lymph node, or neck dissection prior NACT;
2. disease progression during NACT;
3. presence of distant metastasis;
4. pregnancy or lactation;
5. previous malignancy or other concomitant malignant disease.