Validation of Stage <scp>N3</scp> of the Eighth Edition <scp>AJCC</scp> Staging System for Nasopharyngeal Carcinoma

OBJECTIVES To validate stage nodal (N)3 of the 8th edition American Joint Committee on Cancer (AJCC) staging system for nasopharyngeal carcinoma (NPC). METHODS This retrospective cohort study extracted NPC patients from the Surveillance, Epidemiology, and End Results database between 2004 and 2016. Pathologically confirmed patients with complete data of level IV, N3a, and N3b lymph node metastasis were investigated. The included patients were divided into level IV, N3a, and N3b groups. Five-year overall survival (OS) and cancer-specific survival (CSS) were compared among the three groups. RESULTS A total of 693 patients were included: 285 (41.13%) patients in the level IV group, 124 (17.89%) patients in the N3a group, and 284 (40.98%) patients in the N3b group. The 5-year OS (57.1%, 55.0%, and 55.2%) and CSS (64.4%, 63.5%, and 64.4%) were not different among the level IV, N3a, and N3b groups. Multivariate regression analysis revealed that N stage was not an independent prognostic factor for OS (hazard ratio [HR] = 1.03, 95% confidence interval [CI]: 0.91-1.17; P = .65) or CSS (HR = 1.03, 95% CI: 0.89-1.19; P = .70). CONCLUSION Stage N3 of the 8th edition AJCC staging system for NPC is reasonable. LEVEL OF EVIDENCE III Laryngoscope, 131:535-540, 2021.