RESEARCH o l d

Radiation therapy (RT) is the mainstay of definitive ther-apy for nonmetastatic nasopharyngeal carcinoma (NPC). New radiotherapy technique, intensity-modulated radio-therapy (IMRT) has allowed improved dose delivery to NPC tumors while reducing dose to normal tissues [1-4]. However, for patients with intracranial invasion NPC, a common problem encounters in planning IMRT is that the vital structures (such as brain stem, optic nerve, chi-asm) are in close proximity to the tumor volumes, which creates a dilemma in dose optimization as the region of overlap between the target and the normal tissues [5-10]. NPC is sensitive to chemotherapy. Neoadjuvant chemo-therapy has potential advantages of shrinking the tumor bulk before irradiation, as a result narrowing down the tumor target area facilitating the radiotherapy particularl