Maximal lymph nodal diameter on N stage of nasopharyngeal carcinoma.

To assess the maximal lymph nodal diameter on the 8th edition American Joint Committee on Cancer staging system of nasopharyngeal carcinoma (NPC). This study extracted NPC patients between 2004 and 2016 in the Surveillance, Epidemiology, and End Results database. Included patients were divided into 3 groups: ≤3 cm, >3–6 cm, and >6 cm based on the maximal lymph nodal diameter. Cumulative survival curves of 5-year overall survival (OS) and cancer-specific survival (CSS) were calculated using the Kaplan-Meier method between the 3 groups. The 5-year OS (64.0% vs 59.3%, P = .240) and CSS (71.8% vs 67.0%, P = .242) of ≤3 cm and >3–6 cm groups were not different. In contrast, the 5-year OS and CSS were different between >6 cm and ≤3 cm groups, and between >6 cm and >3–6 cm groups. The stratified hazard ratio of OS and CSS was 1.75 (95% confidence interval: 1.25–2.45; P = .001) and 1.77 (95% confidence interval: 1.20–2.60; P = .004) for the >6 cm group in the multivariate regression analysis. It is reasonable that the maximal lymph nodal diameter with >6 cm is classified as stage N3 of the 8th edition American Joint Committee on Cancer staging system for NPC.