Long-term experience with reduced planning target volume margins and intensity-modulated radiotherapy with daily image-guidance for head and neck cancer.

BACKGROUND The purpose of this study was to compare outcomes among patients treated by intensity-modulated radiotherapy (IMRT) with daily image-guided radiotherapy (IGRT) for head and neck cancer according to the margins used to expand the clinical target volume (CTV) to create a planning target volume (PTV). METHODS Three hundred sixty-seven consecutive patients were treated with IMRT for squamous cell carcinoma of the head and neck. The first 103 patients were treated with 5-mm CTV-to-PTV margins. The subsequent 264 patients were treated using reduced (3 mm) margins. RESULTS The 3-year locoregional control for patients treated using 5-mm and 3-mm CTV-to-PTV margins, respectively, was 78% and 80% (p = .75). The incidence of gastrostomy-tube dependence at 1 year was 10% and 3%, respectively (p = .001). The incidence of posttreatment esophageal stricture was 14% and 7%, respectively (p = .01). CONCLUSION The use of reduced (3 mm) CTV-to-PTV margins was associated with reduced late toxicity while maintaining locoregional control.