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.