Selective nodal irradiation for head and neck cancer using intensity-modulated radiotherapy: application of RTOG consensus guidelines in routine clinical practice.

Abstract

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. 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. 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. 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.