Adjuvant therapy improves survival in pT4aN0 oral cavity squamous cell carcinoma with bone invasion

The prognostic significance of bone invasion in oral cavity squamous cell carcinoma (OCSCC) after accounting for tumor size, nodal spread, and surgical margins is controversial. The aim of this study is to determine whether patients with pT4aN0 oral cavity squamous cell carcinoma with bone invasion have improved overall and disease-free survival with adjuvant treatment.

We conducted a retrospective review of medical records from 64 patients with stage pT4aN0 due to mandibular involvement who underwent surgery from 2000 to 2020. Kaplan-Meier analysis compared disease-free survival and overall survival between groups who underwent surgery only versus surgery and adjuvant therapy. The prognostic impact of adjuvant therapy was assessed using multivariate analysis and reported as hazard ratios.

There were no statistically significant differences in clinicopathologic features or mean follow-up between patients who received surgery only and patients who received surgery with RT/CCRT (radiotherapy/concurrent chemoradiation therapy). 5-year disease-free (42.5% versus 65.9%, p = 0.02) and overall survival (43.6% versus 69.0%, p = 0.014) were improved in groups who received surgery and RT/CCRT. Regression analysis controlling for clinicopathologic characteristics, including tumor size, identified radiation as an independent predictor of improved disease-free survival (HR: 0.04, p < 0.001) and overall survival (HR: 0.10, p < 0.001).

Adjuvant RT/CCRT in patients with pT4N0 OCSCC with mandibular bone involvement is associated with improved disease-free and overall survival. This association was significant regardless of tumor pathologic features such as size or margin status. These findings may help guide physicians in counseling patients regarding risks and benefits of adjuvant RT/CCRT and inform practice guidelines.