Number of positive nodes is superior to the lymph node ratio and American Joint Committee on Cancer N staging for the prognosis of surgically treated head and neck squamous cell carcinomas

Abstract

Background: Recent changes in head and neck cancer epidemiology have created a need for improved lymph node prognostics. This article compares the prognostic value of the number of positive nodes (pN) with the value of the lymph node ratio (LNR) and American Joint Committee on Cancer (AJCC) N staging in surgical patients.

Methods: The Surveillance, Epidemiology, and End Results database was used to identify cases of head and neck squamous cell carcinomas from 2004 to 2012. The sample was grouped by the AJCC N stage, LNR, and pN and was analyzed with Kaplan-Meier and multivariate Cox proportional hazards models. The sample was also analyzed by the site of the primary tumor.

Results: This study identified 12,437 patients. Kaplan-Meier survival curves showed superior prognostic ability for LNR and pN staging in comparison with AJCC staging. Patients with a pN value > 5 had the worst overall survival (5-year survival rate, 16%). Patients with oropharyngeal tumors had better outcomes for all groupings, and a pN value > 5 for oropharyngeal cancers was associated with decreased survival. Multivariate regressions demonstrated larger hazard ratios (HRs) and a lower Akaike information criterion for the pN model versus the AJCC stage and LNR models. The HRs were 1.78 (95% confidence interval, 1.62-1.95) for a pN value of 1, 2.53 (95% confidence interval, 2.32-2.75) for a pN value of 2 to 5, and 4.64 (95% confidence interval, 4.18-5.14) for a pN value > 5.

Conclusions: The pN models demonstrated superior prognostic value in comparison with the LNR and AJCC N staging. Future modifications of the nodal staging system should be based on the pN with a separate system for oropharyngeal cancers. Future trials should consider examining adjuvant treatment escalation in patients with >5 lymph nodes. Cancer 2016;122:1388-1397. © 2016 American Cancer Society.

Keywords: head and neck cancer; lymph nodes; oral cancer; oropharyngeal cancer; squamous cell carcinoma; staging.