Purpose: We have been using intensity-modulated radiotherapy (IMRT) for selective neck irradiation. This article presents an analysis of patterns of failure and their dosimetric correlation.
Methods and materials: Between October 2003 and January 2008, 83 patients with head-and-neck cancer were treated with IMRT. Nodal levels were contoured as per the Radiation Therapy Oncology Group (RTOG) consensus guidelines.
Results: There were 32 relapses with 23 local relapses (21 local relapses alone and 2 local and regional relapses, simultaneously), 9 regional relapses (including 2 simultaneous local and regional relapses), and 5 distant relapses, of which 2 patients had local relapses. At 2 and 3 years, the locoregional relapse-free survival rates were was 68.3% and 60.8%, respectively, while the overall survival rates were 84.1% and 81.7%, respectively. Subgroup analyses revealed significant differences in locoregional relapse-free survival rates for total treatment times of <53 days vs. >53 days, a volume of CTV1PTV (i.e., the volume prescribed 70 Gy) <177 cc vs. >177 cc, a V100 for CTV1PTV of <91% vs. >91%, and a minimum dose to CTV1PTV of <54 Gy vs. >54 Gy. There were no failures in the elective nodal volume, substantiating both the nodal selection criteria and the RTOG consensus guidelines for delineation of neck node levels.
Conclusions: IMRT for head-neck cancer is feasible, using elective nodal selection criteria along with RTOG consensus guidelines for the radiological boundaries of levels of neck nodes.