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

Abstract

Objective: To investigate clinical evidence for defining the indications of prophylactic level IB radiotherapy in nasopharyngeal carcinoma (NPC). Methods: We conducted a phase 2 prospective study in 116 newly diagnosed patients with NPC treated by intensity-modulated radiotherapy (IMRT). Whether level IB was irradiated 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 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 16months (range, 1-26 months). None patients developed failures at level IB. The 1-year overall survival (OS), locoregional recurrence-free survival (LRRFS) and distant metastasis-free survival (DMFS) rates were 98.3%, 97.2% and 95.8%, respectively. At 12 months xerostomia side-effects were reported 90 of 126 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.

Radiation oncology for the rhinologist

“…Numerous recent studies have dedicated their research efforts to assessing the outcomes and toxicity profiles associated with the controversial omission of radiation treatment to select neck levels in NPC [38–40,41 ▪ ]. Tang et al [42 ▪▪ ] published their results of an open label, noninferiority, multicenter randomized phase 3 trial, reporting on 446 N0/N1 stage patients from three different centers in China.…”

“…In an endeavor to minimize irradiation of level Ib and mitigate its associated complications, Zhang et al [40] have devised a risk score model based on the maximal axial diameter and extracapsular spread of level IIa nodes, and submandibular gland involvement or compression. In their phase 2 prospective study, level Ib was radiated based on the calculated risk score for each patient.…”

“…6 of the most recent American Society of Clinical Oncology (ASCO) guidelines states the delineation of elective nodal volumes in NPC should cover the bilateral neck from the retropharyngeal lymph nodes to level IV and V[37 && ]. This moderate-in-strength, informal-consensustype recommendation does permit omission of level Ib under certain circumstances, and also mentions omission of lower neck volume in the uninvolved side of the neck may be considered if the neck contains no equivocal lymph node(s).Numerous recent studies have dedicated their research efforts to assessing the outcomes and toxicity profiles associated with the controversial omission of radiation treatment to select neck levels in NPC[38][39][40]41 & ]. Tang et al [42 && ] published their results of an open label, noninferiority, multicenter randomized phase 3 trial, reporting on 446 N0/N1 stage patients from three different centers in China.…”