Oncologic outcomes of microscopic tumor cut-through in locally advanced oral squamous cell carcinoma

Introduction: The gold standard treatment of oral cavity squamous cell carcinoma (OCSCC) is surgical resection; however, standardization of the margins and the role of frozen section are still debatable. Microscopic tumor cut-thought (MTCT) occurs when the surgeon has an initial positive frozen section margin that is cleared with further resection to negative. Objective: This study aims to determine the impact of MTCT on local recurrence and disease-specific survival in patients with locally advanced T3-T4 OCSCC and compare it with other clinicopathological variables. Methods: A retrospective database analysis of patients diagnosed with locally advanced T3-T4 OCSCC surgically treated and submitted to intraoperative frozen section guiding the margin status. Survival was analyzed using the Kaplan-Meier estimator followed by the Cox model for multivariate analysis. Results: We analyzed 475 patients who met inclusion criteria: MTCT occurred in 29 patients (6.11%) and local recurrence was observed in 131 patients (27.6%). MTCT had an impact on univariate (HR 2.205; 95% CI 1.243 – 3.914; p =0.007) and multivariate (HR 1.851; 95% CI 1.285 – 2.666; p =0.001) analyses. Similar results were found for disease-specific survival: univariate (HZ 1.669; 95% CI 1.056 – 2.635; p =0.028) and multivariate (HZ 1.307; 95% CI 0.816 – 2.092; p =0.265) analyses. A total of 231 patients (48.6%) had died of cancer by the end of follow-up. The best predictor for compromised frozen sections was tumor depth of invasion. Conclusion: Even after negative final margins, MTCT is an important factor associated with poorer outcome, and treatment intensification should be considered in these patients.