Adjuvant radiotherapy improves overall survival for patients with lymph node-positive head and neck squamous cell carcinoma

BACKGROUND: Although adjuvant radiotherapy (RT) is often recommended for locally advanced squamous cell carcinoma of the head and neck (HNSCC), its effect on overall or cancer-specific survival has not been clearly demonstrated. In the current study, the frequency and effect of adjuvant RT on overall survival was investigated in patients with resected lymph node-positive head and neck cancer. METHODS: Within the Surveillance, Epidemiology, and End Results (SEER) database, patients were selected with lymph node-positive HNSCC (American Joint Committee on Cancer and SEER stage 3/4) who were treated either with surgery alone or surgery and RT and were diagnosed between 1988 and 2001. A total of 8795 patients who met the inclusion criteria for analysis comprised the study population, with a median follow-up of 4.3 years for patients still alive at the time of last follow-up. RESULTS: Adjuvant RT was utilized in 84% of patients. Adjuvant RT improved the 5-year overall survival (43.2% [95% confidence interval (95% CI), 41.9-44.4%] for surgery + RT vs 33.4% [95% CI, 30.7-36.0%] for surgery alone; P < .001) and cancer-specific survival (50.9% for surgery + RT vs 42.1% for surgery) on univariate analysis. On multivariate analysis, adjuvant RT (hazards ratio [HR] of 0.78; 95% CI, 0.71-0.86 [P < .001]) remained a significant predictor of improved survival. The significant benefit of radiation on overall survival was noted for lymph node-positive patients with both primary tumors localized to the involved organ (HR of 0.81; 95% CI, 0.71-0.94 [P = .007]) and more locally invasive primary tumors (HR of 0.77; 95% CI, 0.68-0.87 [P < .001]). CONCLUSIONS: In what to the authors' knowledge is the largest reported analysis of adjuvant RT in patients with locally advanced HNSCC published to date, adjuvant RT resulted in an approximately 10% absolute increase in 5-year cancer-specific survival and overall survival for patients with lymph node-positive HNSCC compared with surgery alone. Despite combined surgery and adjuvant RT, outcomes in this high-risk population remain suboptimal, emphasizing the need for continued investigation of innovative treatment approaches.