Margin to Depth of Invasion Ratio on Oncologic Outcomes in Nodal Negative Oral Tongue Cancer

Introduction: This study aimed to evaluate the prognostic significance of the margin to depth of invasion ratio (MDR) in pathological nodal-negative (pN0) oral tongue squamous cell carcinoma (OTSCC).

Methods: A total of 296 patients with pN0 OTSCC who underwent primary radical surgery and high-quality neck dissection (lymph node yield ≥ 18) without positive margin ( < 1 mm) between 2007 and 2017 were included in this study. Cox proportional hazards models were utilized to identify factors associated with survival outcomes, including cancer specific survival (CSS) and relapse free survival (RFS).

Results: The optimal cut-off for MDR was determined to be 0.29. For those with MDR ≥0.29, the 5-year CSS and RFS were significantly superior compared to those with MDR < 0.29 (CSS: 92.8% versus 71.5%, p< 0.001; RFS: 89.3% versus 67.9%, p< 0.001). In the multivariate Cox model, a low MDR emerged as an independent negative prognosticator of CSS (HR: 2.707, 95% CI: 1.167–6.282, p=0.02) and RFS (HR: 2.535, 95% CI:1.071–6, p=0.034). In radical surgery without adjuvant therapy subgroup patients, patients with a low MDR had significantly poorer CSS and RFS than patients with a high MDR (both p < 0.001) .

Conclusions: For pN0 OTSCC patients without positive margin ( < 1mm), the survival outcome between MDR ≥ 0.29 group and MDR < 0.29 group was significantly different. The MDR < 0.29 group had significantly higher risk of relapse and tongue cancer specific survival that may warrant adjuvant treatment.