Abstract: Objective To analyze the therapy effect and influence factor of late course three-dimensional conformal radiotherapy(3DCRT)on untreated patients with nasopharyngeal carcinoma(NPC),and to evaluate the feasibility of this therapy.Methods 125 untreated patients with NPC that received late course 3DCRT from January 1999 to December 2007 were retrospectively analyzed,by calculating the local control rate,distant metastasis-free survival rate,tumor-free survival rate and overall survival rate.The overall survival rate of patients with parapharyngeal space invasion or skull base invasion was also calculated.Results The 3-,5-and 10-year local control rates were 98%,95% and 94%,respectively.The distant metastasis-free survival rates were 96%,94% and 86%,respectively.The tumor-free survival rates were 98%,97% and 89%,respectively.The overall survival rates were 93%,86% and 76%,respectively.Overall survival rates with parapharyngeal space invasion or skull base invasion were 98.0%,94.0%,92.0% and 89.0%,79.0%,50.0% for 3-,5-and 10-year,respectively.Conclusions There is satisfactory effect of late course 3DCRT on the untreated patients with NPC.There is still good survival rate even when the patients were with parapharyngeal space invasion or skull base invasion.3DCRT could improve the treatment benefit ratio without obviously increase the costs comparing to that with conventional radiotherapy.The late course 3DCRT is a good selection for the untreated patients with NPC.

Key words: Nasopharyngeal carcinoma, Three dimensional conformal radiotherapy, Invasion, Prognosis