Nodal Metastasis Count and Oncologic Outcomes in Head and Neck Cancer: A Secondary Analysis of NRG/RTOG 9501, NRG/RTOG 0234, and EORTC 22931

Purpose: A better understanding of the relationship between the spread of head and neck squamous cell carcinoma (HNSCC) to regional lymph nodes (LNs) and the frequency and manner of treatment failure should help design better treatment intensification strategies. In this study, we evaluated the relationship between recurrence patterns, mortality, and number of pathologically positive (+) LNs in HNSCC in 3 prospective randomized controlled trials. Methods and Materials: We performed a secondary analysis of 947 patients with HNSCC enrolled in RTOG 9501 (n = 410), RTOG 0234 (n = 203), and EORTC 22931 (n = 334) undergoing surgery and postoperative radiation +/- systemic therapy. Multi variable models were constructed for overall survival (OS), disease-free survival (DFS), locoregional relapse (LRR), and distant metastases (DM). Restricted cubic splines were used to model the nonlinear relationship between +LN number and outcomes. Results: In multivariable analysis, OS and DFS decreased with each +LN without plateau, most pronounced up to 5 +LNs (OS: hazard ratio [HR], 1.21 per +LN; 95% confidence interval [CI], 1.10-1.34; P < .001; DFS: HR per +LN, 1.19; 95% CI, 1.08-1.30; P < .001) and more gradually beyond this (OS: HR per +LN, 1.02; 95% CI, 1.01-1.06; P < .001; DFS: HR per +LN, 1.04; 95% CI, 1.02-1.06; P < .001). In contrast to LRR risk, which increased sharply up to 5 +LNs (HR per +LN, 1.28; 95% CI, 1.10-1.50; P <.001) but plateaued beyond this (HR per +LN, 1.00; 95% CI, 0.96-1.04; P = .98), DM risk increased continuously with increasing +LNs (<= 5 +LNs: HR per +LN, 1.10; 95% CI, 1.01-1.20; P = .04; > 5 +LNs: HR per +LN, 1.05; 95% CI, 1.02-1.08; P = .003). Conclusions: In high-risk resected HNSCC, increased mortality was associated with increased +LN count. LRR and DM risk both increased in parallel up to 5 +LNs, but only DM continued to increase for further +LN increases. These differing recurrence patterns can help inform design of future treatments. (C) 2022 Elsevier Inc. All rights reserved.