Beyond positive margins and extracapsular extension: Evaluating the utilization and clinical impact of postoperative chemoradiotherapy in resected locally advanced head and neck cancer

Purpose: To examine recent utilization and survival outcomes associated with use of adjuvant chemoradiotherapy (CRT) for patients with resected locally advanced head and neck cancer (LAHNC) with negative surgical margins (SM negative) and no extracapsular extension (ECE). Materials and Methods: We conducted a retrospective observational cohort study using the National Cancer Database evaluating patients diagnosed in 2004 to 2012 with AJCC stage III to IVB squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, and larynx treated with definitive surgery and adjuvant radiotherapy (RT) or CRT. We identified a subset of patients with SM negative and no ECE (n = 10,870). We determined factors associated with CRT use and examined overall survival of patients receiving CRT versus RT. We further evaluated survival outcomes by number of lymph nodes involved to assess whether this was associated with benefit from CRT. Results: Among patients with resected LAHNC with SM negative and no ECE, 47% received adjuvant CRT. The use of CRT varied substantially according to several factors, including patient age, contralateral/bulky neck disease, increasing number of positive lymph nodes, and lower neck disease. CRT was associated with a statistically significant improvement in overall survival compared with RT alone (hazard ratio, 0.90; 95% CI, 0.86 to 0.94; P < .001). Survival benefits of CRT versus RT alone increased in patients with multiple positive lymph nodes. Conclusion: The use of adjuvant CRT in patients with resected LAHNC with SM negative and no ECE is common. Substantial practice variation as well as the survival differences observed in this study support the conduct of additional research to guide personalized treatment approaches in this setting. The number of positive lymph nodes seems to be an appropriate selection factor for further investigation of CRT in such patients.