Adjuvant radiotherapy and survival for patients with node-positive head and neck cancer: an analysis by primary site and nodal stage.

PURPOSE: Adjuvant radiotherapy (RT) is frequently recommended for node-positive head and neck squamous cell carcinoma (HNSCC) treated with primary surgery. The impact of RT on survival for various subgroups of node-positive HNSCC has not been clearly demonstrated. METHODS AND MATERIALS: Within the Surveillance, Epidemiology, and End Results (SEER) Database, we identified 5297 patients with node-positive (N1 to N3) HNSCC treated with definitive surgery with or without adjuvant RT between 1988 and 2001. The median follow-up was 4.4 years.
RESULTS: Adjuvant RT significantly improved 5-year overall survival (46.3%: 95% confidence interval [CI], 44.7-48.0% for surgery + RT, vs. 35.2%: 95% CI, 32.0-38.5% for surgery alone, p < 0.001) and cancer-specific survival (54.8%: 95% CI, 53.2-56.4% for surgery + RT, vs. 46.2% for surgery alone 95% CI, 42.4-50.0%, p < 0.05). Use of adjuvant RT remained a significant predictor of survival on multivariable analysis (hazard ratio [HR], 0.75; 95% CI, 0.68-0.83; p < 0.001). Subset analyses demonstrated that adjuvant RT was associated with significantly improved survival for N1 (HR, 0.78; 95% CI; 0.67-0.90; p = 0.001), N2a (HR, 0.82; 95% CI, 0.67-0.99, p = 0.048) and N2b to N3 nodal disease (HR, 0.62; 95% CI, 0.51-0.75; p < 0.001). Adjuvant RT increased overall survival for node-positive patients with oropharynx (HR, 0.72; 95% CI, 0.57-0.90; p = 0.004), hypopharynx (HR, 0.66; 95% CI, 0.49 to 0.88; p = 0.004), larynx (HR, 0.66; 95% CI, 0.52-0.84; p = 0.001), and oral cavity (HR, 0.84; 95% CI, 0.73-0.98; p = 0.025) primary tumors.
CONCLUSIONS: In a large population-based analysis, adjuvant RT significantly improves overall survival for patients with node-positive HNSCC. All nodal stages, including N1, appear to benefit from the addition of RT to definitive surgery.