Intensity‐modulated proton therapy for nasopharyngeal carcinoma: Decreased radiation dose to normal structures and encouraging clinical outcomes

BACKGROUND: Intensity-modulated proton therapy (IMPT) has the potential to spare dose to organs at risk (OAR) when compared to intensity-modulated radiotherapy (IMRT) while maintaining excellent clinical outcomes. METHODS: Ten patients with nasopharyngeal carcinoma (NPC) were identified for whom IMPT was planned; 9 patients also had a comparison photon-based IMRT plan generated. Dosimetric comparison of mean radiation dose to 29 adjacent OAR was performed. Disease control, survival, and toxicity outcomes were collected from the medical records. RESULTS: There were significant differences in mean doses in 15 of the 29 OAR; 13 OAR received lower mean dose with proton-based plans. Median follow-up was 24.5 months (range, 19-32 months). Two-year locoregional control was 100% and the 2-year overall survival was 88.9%. CONCLUSION: We observed dosimetric advantages conferred by IMPT compared to IMRT. Further study is needed to determine if these translate into reduced toxicity and/or improved disease control.