Margin to Depth of Invasion Ratio on Oncologic Outcomes in Node-Negative Oral Tongue Cancer.

Abstract

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). Case series with chart review. Tertiary academic medical center. 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 retrospectively analyzed. Cox proportional hazards models were utilized to identify factors associated with survival outcomes, including cancer-specific survival (CSS) and relapse-free survival (RFS). A total of 296 patients were enrolled in this study. The optimal cutoff value for MDR was determined to be 0.29. For those with high MDR, the 5-year CSS and RFS were significantly superior compared to those with low MDR (CSS: 92.8% vs 71.5%, P < .001; RFS: 89.3% vs 67.9%, P < .001). In the multivariate Cox model, a low MDR remained an independent negative prognosticator of CSS (HR: 2.846, 95% CI: 1.229-6.593, P = .015) and RFS (HR: 2.661, 95% CI: 1.126-6.288, P = .026). 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 < .001). Among pN0 OTSCC patients with negative surgical margins (≥1 mm), survival outcomes differed significantly between the high and low MDR groups. Patients with a low MDR had a markedly higher risk of recurrence and poorer cancer-specific survival, suggesting that adjuvant treatment may be warranted for this subgroup.