Adjuvant Radiotherapy for Early-Stage Oral Tongue Cancer: Insights From the NCDB Based on Grade.

Background: Oral tongue squamous cell carcinoma (OTSCC) incidence is rising in the United States. While early-stage (pT1-2N0M0) OTSCC is primarily managed with surgery, the role of postoperative radiotherapy (PORT) remains debated, particularly in moderate-to-poor differentiation. Current guidelines do not recommend PORT based on histologic grade alone, yet a retrospective study by Tian et al. found PORT improved survival in moderately-to-poorly differentiated OTSCC in a Chinese cohort. We aimed to validate these findings in a US population.

Methods: A retrospective cohort study using the National Cancer Database (2004-2022) identified patients with pT1-2N0M0 OTSCC treated with surgery or surgery plus PORT. After stringent inclusion criteria, 3562 patients remained, including 456 (12.8%) who received PORT. Propensity score matching (PSM) balanced key prognostic factors, and survival was assessed using Kaplan-Meier analysis and multivariable Cox proportional hazards models.

Results: PORT did not improve OS in well- or moderately differentiated tumors. However, in poorly differentiated tumors, PORT was associated with a significant survival benefit (HR: 0.53, 95% CI: 0.30-0.92, p = 0.025) before and after PSM. This effect persisted in multivariable analysis (HR: 0.56, 95% CI: 0.31-0.99, p = 0.047) and after excluding patients with lymphovascular invasion (HR: 0.48, 95% CI: 0.27-0.87, p = 0.016).

Conclusions: These findings validate and extend prior international data, demonstrating a PORT-associated survival benefit in poorly differentiated early-stage OTSCC. The lack of benefit in well- and moderately differentiated tumors underscores the need for individualized treatment approaches. Prospective studies are warranted to refine risk stratification and optimize clinical guidelines.