Role of adjuvant radiation in patients with squamous cell carcinomas of the oral cavity.

Abstract

6042 Background: Although surgery is the initial treatment of choice for patients with stage III squamous cell carcinoma (SCC) of the oral cavity (OC), the role of adjuvant radiotherapy (RT) remains undefined. We evaluated the differences in outcome according to stage subsets and use of adjuvant RT. Methods: The Surveillance Epidemiology and End Results (SEER) database was queried for patients with SCCOC, treated with surgery (S), RT, or both (SRT); older than 21 years; and diagnosed between 2004 and 2009. Patients with extracapsular lymph node extension or multiple primary cancers were excluded. Overall Survival (OS) rates were estimated by the Kaplan-Meier method and compared using log-rank testing as well as Cox proportional hazards. Results: Among the 1,051 patients meeting eligibility criteria, the most common treatment was SRT (49.1%), followed by S alone (28.9%), and RT alone (22.0%). The 5-year OS ranged from 33.3% in T3N1 to 52.8% in T1N1. Compared to S alone, the addition of RT improved 5-year OS in the entire cohort from 39.5% to 51.1% (HR 0.69, 95% CI 0.54-0.87, p = 0.002). This benefit, however, was significant only for stage T3N0 with a trend towards improvement in the T3N1 group. No significant benefit was observed in T1N1 or T2N1 disease (Table). Conclusions: Stage III SCC of the oral cavity is a heterogeneous disease with significant differences in survival according to its subsets. Adjuvant RT was associated with improved survival for patients with stage T3N0 disease but not T1N1 or T2N1. The benefit of RT in T3N1 cases did not reach statistical significance likely due to the small number of patients. If confirmed in prospective studies, further subdivision of stage III SCC of OC may be necessary, and the indication for RT may be restricted to patients with T3 disease. [Table: see text]