A Prospective Study on Defining the Indications of Prophylactic Level IB Radiotherapy in Nasopharyngeal Carcinoma Based on a Risk Score Model.

ABSTRACT

OBJECTIVE: The aim of the study was to investigate clinical evidence for defining the indications of prophylactic level IB radiotherapy (RT) in nasopharyngeal carcinoma (NPC). METHODS: We conducted a phase 2 prospective study in 116 newly diagnosed patients with NPC treated by intensity-modulated RT. Whether level IB was irradiated is based on the risk score model (RSM). Two groups based on RSM were obtained low risk and high risk. Omission of level IB irradiation was conducted in the low-risk group, otherwise level IB was contoured as part of the treatment target. Grade 2 or worse xerostomia at 12 months was assessed by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-H&N35 questionnaire. RESULTS: At a median follow-up of 16 months (range, 1-26 months), none of the patients developed failures at level IB. The 1-year overall survival, locoregional recurrence-free survival, and distant metastasis-free survival rates were 98.3%, 97.2%, and 95.8%, respectively. At 12 months xerostomia side-effects were reported in 90 of 116 alive patients; grade 2 or worse xerostomia at 12 months was significantly lower in the low-risk group than in the high-risk group. CONCLUSION: Omission of level IB irradiation was feasible for patients with low-risk IB lymph nodes metastasis.