Margin‐To‐Depth of Invasion Ratio: New Standard for T1 / T2 OSCC Surgical Margin Assessment?

OBJECTIVES: To identify factors associated with local recurrence of oral squamous cell carcinoma, with particular attention to the margin-to-depth-of-invasion ratio. METHODS: We performed a retrospective cohort study of 98 patients with pathological T1 or T2 oral squamous cell carcinoma treated between 2013 and 2021. The prognostic relevance of clinicopathological variables-including resection-margin distance and the margin-to-depth-of-invasion ratio-was evaluated. RESULTS: The margin-to-depth-of-invasion ratio was significantly associated with local recurrence (cutoff = 0.945, p = 0.014) and with disease-free survival (ratio < 0.945: 60.1%; ratio ≥ 0.945: 83.6%; p = 0.010); similar findings were observed for the close-margin subgroup (ratio < 0.945: 60.2%; ratio ≥ 0.945: 100%; p = 0.016). Close margins alone were not predictive of local recurrence (p = 0.258). In addition, no significant difference in disease-free survival was detected between cases with close margins and a ratio ≥ 0.945 and those with clear margins (100% vs. 80.2%; p = 0.094). CONCLUSIONS: The margin-to-depth-of-invasion ratio may serve as a practical criterion for determining the minimum resection distance and the need for postoperative adjuvant therapy in patients with close margins.