The feasibility of omitting irradiation to the contralateral lower neck in stage N1 nasopharyngeal carcinoma patients

PURPOSE This study was conducted to analyze the feasibility of omitting irradiation to the contralateral lower neck in stage N1 nasopharyngeal carcinoma (NPC) patients. MATERIALS AND METHODS From July 2008 to January 2012, 52 patients with stage N1 NPC were analyzed. All patients were treated with intensity-modulated radiation therapy (IMRT) and received bilateral upper neck irradiation to levels II, III and VA and ipsilateral lower neck irradiation to levels IV and VB. The contralateral lower neck irradiation was omitted. RESULTS The median follow-up was 29 months (range, 12-52 months). The 3-year overall survival (OS) rate, progress-free survival (PFS), local failure-free (LFS), nodal recurrence-free survival (NFS) and distant metastasis-free survival (DMFS) rates were 92.2%, 94.1%, 94.3%, 98% and 94.1%, respectively. Only one patient developed a neck recurrence in the irradiation field, while no patients experienced out-of-field nodal recurrence. Univariate analysis suggested that T classification was the only significant prognostic factor for overall survival, and age was significantly associated with PFS. Multivariate analyses indicated that age was also a predictor for overall survival. The elective neck irradiation procedure was not a significant predictor for all of the treatment results. CONCLUSION Selective irradiation to bilateral levels of II, III and VA and unilateral levels of IV and VB, omitted the contralateral lower neck in a proportion of patients with N1 stage NPC was safe and practicable.