Hyperfractionated Intensity-modulated Radiotherapy (IMRT) Versus Conventional Fraction IMRT for Patients With Loco-regionally Recurrent Nasopharyngeal Carcinoma.

Local recurrence is one of the most challenging issues faced with nasopharyngeal carcinoma (NPC) patients. 8.4% to 10.9% of the patients developed recurrent diseases at the primary or/and regional site after definitive radiotherapy. Although some patients with limited recurrent lesions underwent surgery, the main treatment for these recurrent NPC patients was still re-irradiation. Multiple retrospective and prospective studies have reported: under the condition of conventional fraction IMRT with the total dose of 60 gray (Gy) (division 27 times, once a day, every 2.2Gy), you can get a better local tumor control rate and survival outcome. However, the patients still underwent some severe late complications including nasopharyngeal necrosis, nasopharyngeal bleeding, temporal lobe necrosis, with the incidence rates of 28.8%, 18.6%, 20.3%, respectively. Approximately 50% of recurrent NPC patients died of these severe late complications, significantly compromising the overall survival rate of the patients. Previous studies showed that hyperfractionated radiotherapy could reduce severe late complication rates significantly, without affecting the local control rate. Indeed, we found that under the condition of equal irradiation time and tumor equivalent dosage between hyperfractionated IMRT (total dose of 65Gy, division 54 times, twice a day, once 1.2Gy, irradiation interval of 6-8 hours) and conventional fraction IMRT (total dose of 60Gy, division 27 times, once a day, every 2.2Gy), the normal late responding tissues equivalent dosage( EQD2) significantly decreased compared with conventional fraction IMRT. Therefore, the use of hyperfractionated IMRT is expected to decrease severe late complications rates, thereby improving the quality of life and overall survival of patients.