Prognostic Value of Lymph Node Status is Greater Than Lymph Node Ratio and AJCC N Staging for Head and Neck Squamous Cell Carcinomas

Changes in the epidemiology of head and neck cancers have created a need for new lymph node prognostics. The lymph node ratio (LNR) has been proposed as an alternative staging system, but this metric has limitations that may attenuate its prognostic value. This study sought to test the prognostic value of the lymph node status (pN) and compare it to the LNR and American Joint Committee on Cancer (AJCC) N staging. The Survival, Epidemiology, and End Results (SEER) database was used to identify surgical cases from 2004 to 2012. The study sample was grouped based on AJCC N stage, LNR, and pN and analyzed using the Kaplan-Meier method and multivariate Cox proportional hazard models. Models were compared using the Akaiki Information Criterion (AIC). The sample was also analyzed by site of primary tumor. We identified 12,437 patients in the SEER database for analysis. Distribution of nodal staging was 5282 N0 patients, 2483 N1 patients, 4454 N2 patients, and 218 N3 patients. Twenty-four percent of patients had an oropharyngeal primary. Kaplan-Meier survival curves showed improved prognostic ability for pN and LNR staging relative to the AJCC system. Tumors with >5 positive nodes were associated with the worst overall survival (5-year survival rate = 16%). Oropharyngeal tumors had better outcomes for all groupings in all staging systems as compared to those in nonoropharyngeal sites. Using the pN staging system, >5 positive nodes in oropharyngeal tumors was strongly associated with decreased survival (5-year survival rate = 53%), while patients with 0 to 5 positive nodes had similar 5-year survival.Multivariate regression outputs demonstrated more prognostic hazard ratios and a lower AIC for the pN model compared to the AJCC N stage and LNR models (Table 1). Hazard ratios were 1.78 (95% confidence interval [CI], 1.62-1.95) for 1 positive node, 2.53 (95% CI, 2.32-2.75) for 2-5 positive nodes, and 4.64 (95% CI, 4.18-5.14) for >5 nodes. The pN models demonstrated superior prognostic value compared to the LNR and AJCC N staging in the overall study sample and site-specific analyses. Future modifications of the nodal staging system should be based on the lymph node status, with consideration given to a separate system for oropharyngeal cancers. Patients with more than 5 positive nodes have significantly worse survival in all subsites and should be considered for alternative treatment regimens.Abstract 203; Table 1Multivariate regression outputs showing hazard ratios for AJCC N stage, pN, and LNR groups with 95% confidence intervals.AJCC N stageHR(95% CI)pNHR(95% CI)LNRHR(95% CI)N11.98(1.81-2.16)11.78(1.62-1.95)0-6%1.81(1.66-1.98)N2a1.95(1.72-2.42)2-52.53(2.32- 2.75)6%-12.5%2.52(2.29 -2.77)N2b2.85(2.66-3.16)>54.64(4.18 -5.14)≥12.5%3.69(3.37 -4.05)N2c3.78(3.30-4.15)N32.52(2.05-3.28) Open table in a new tab