Relationship between level of lymph node metastasis (LNM) and survival in head and neck squamous cell carcinoma (HNSCC).

6087 Background: Evidence from small cohorts suggests that level of LNM predicts survival in patients with HNSCC. This study sought to investigate the prognostic value of level of LNM in a large populational database and contrast it with the current AJCC classification of lymph node involvement. Methods: SEER registry was queried for patients with stage I-IVB HNSCC of oral cavity (OC), oropharynx (OP), larynx (LAR) and hypopharynx (HP) diagnosed from 2004 to 2009 (N=39,699, median follow-up 2.3 years). Each anatomic group was divided into 3 subgroups based on level of LNM (no LNM, LNM to levels 1-3, 4 or 5), and 4 subgroups based on AJCC classification (N0, N1, N2, N3). Overall survival (OS) in each subgroup was computed (Kaplan-Meier method) and compared (log-rank test). Concordance statistics (C-index) were used to assess the accuracy of LNM classification by level vs AJCC in predicting OS. Results: Both AJCC and level of LNM-based classifications predicted OS in patients with OC, LAR, and HP cancers. F...