Parameters to assess the necessity of adjuvant therapy for early-stage oral squamous cell carcinoma

Objective: One-third of head and neck squamous cell carcinomas are early-stage oral cavity squamous cell carcinomas (OCSCC). Despite a high curative rate, 20% of early-stage OCSCC patients do not achieve long-term survival. This study evaluates the role of adjuvant therapy (ADJ) in delaying disease progression and prolonging survival. Methods: This single-institute retrospective cohort study enrolled 481 early-stage OCSCC patients, 16% (78/481) of whom received ADJ. It was reported according to the STROBE guidelines. Cox proportional hazards regression and Kaplan–Meier survival curves were employed to identify suitable candidates for ADJ. Results: The 5-year locoregional recurrence-free survival (LR-RFS) and overall survival rates were 73.2% and 84.9%, respectively. Positive margins and advanced depth of invasion (DOI) were independent predictors of LR-RFS. For patients with positive margins, adjuvant chemoradiotherapy (CRT) was superior to adjuvant radiotherapy alone in improving LR-RFS (hazard ratios for adjuvant CRT vs. none, 0.042; adjuvant radiotherapy alone vs. none, 0.702). Excluding positive margins, advanced DOI was the most critical factor in assessing the need for ADJ. Positive margins and advanced DOI were more appropriate criteria than EORTC 22931/RTOG 9501 for evaluating adjuvant CRT. Conclusions: Adjuvant CRT was indicated for patients with positive margins and advanced DOI to improve survival outcomes.