Lymph Node Status and Outcomes for Nasopharyngeal Carcinoma According to Histological Subtypes: A SEER Population-Based Retrospective Analysis.

INTRODUCTION: We aimed to investigate the clinical effect of histological subtypes on survival in nasopharyngeal carcinoma (NPC), and assess the effect of nodal stage on outcome according to histological subtypes. METHODS: Patients with non-metastatic NPC were identified from the Surveillance, Epidemiology and End-Results (SEER) database between 2004 and 2014. Statistical analysis was performed using the chi-squared test, Kaplan-Meier methods, and multivariate Cox regression models. RESULTS: We identified 2845 patients in this study including 1218 (42.8%), 849 (29.8%), and 778 (27.3%) patients with keratinizing squamous cell carcinoma (KSCC), differentiated non-keratinizing squamous cell carcinoma (DNKSCC), and undifferentiated non-keratinizing squamous cell carcinoma (UNKSCC), respectively. The multivariate analysis indicated that patients with UNKSCC subtype had better NPC-specific survival (NPC-SS) (P < 0.001) compared to KSCC (P < 0.001) and DNKSCC (P < 0.001) patients. The 5-year NPC-SS was 75.2%, 77.9%, and 88.9% in patients with KSCC, DNKSCC, UNKSCC, respectively (P < 0.001). Subgroup analysis showed that advanced nodal stage was related to lower NPC-SS in patients with DNKSCC and UNKSCC but not in patients with KSCC. CONCLUSIONS: Histology is an independent prognostic factor in patients with NPC. However, advanced nodal stage is not associated with lower survival in KSCC.