The Role of Elective Nodal Irradiation in Treating Clinically Node-Negative Sinonasal Squamous Cell Carcinoma

Abstract

PurposeThis study aims to examine the role of elective nodal irradiation (ENI) in clinically node-negative (cN0) sinonasal squamous cell carcinoma (SNSCC) and to define the optimal radiation fields for ENI. Methods and MaterialsWe retrospectively reviewed 368 cN0 SNSCC patients treated between 2009 and 2021. The study evaluated the impact of ENI on overall survival (OS), progression-free survival (PFS), regional-failure-free survival (RFS), and distant metastasis-free survival (DMFS), along with the coverage areas of ENI. ResultsThe majority of patients underwent surgery (n=316, 85.9%), with 75% (n=276) having tumors in the maxillary sinus or nasal cavity and 67.7% (n=249) presenting with T4 disease. Additionally, 32.3% (n=119) of the tumors were poorly differentiated. The 5-year OS, PFS, RFS, and DMFS rates were 59.3%, 54.0%, 57.6%, and 58.8%, respectively. ENI was performed in 217 patients (59%), with sixteen experiencing neck relapse during follow-up. While ENI did not enhance survival rates, it significantly reduced the overall regional-failure rate (7.9% vs. 1.8%, χ2 =7.98, p<0.01) and the cumulative incidence of regional failure (p=0.045). Additionally, the subgroups with maxillary sinus origin (2.33% vs. 13.51%, p=0.025), T4 stage (1.80% vs. 8.54%, p=0.028), and poor differentiation (2.44% vs. 13.51%, p=0.029) had higher cumulative incidences of regional failure in patients without ENI. No significant difference was observed in survival and regional failure rates between patients treated with ENI to levels Ib and II with or without level III, as well as between cN0 patients with non-midline crossing lesions receiving unilateral or bilateral ENI. ConclusionsDespite no survival benefit, ENI significantly decreases the regional failure rate in cN0 SNSCC patients. For primary lesions not crossing the midline, ipsilateral ENI targeting levels Ib and II proves to be an effective strategy.