Prognostic Impact of Intraoperative Microscopic Cut-Through on Frozen Section in Oral Cavity Squamous Cell Carcinoma

Objective: Although the literature suggests that a positive tumour margin on permanent section portends a poor oncologic outcome, the prognostic implication of microscopic tumour cut-through (ie, positive tumour margin on intraoperative frozen section) that is surgically revised to a negative final margin on permanent section is currently unclear. Therefore, this study aimed to analyze the influence of microscopic tumour cut-through on disease recurrence and survival and to establish clinicopathologic variables associated with tumour cut-through. Design: A retrospective chart review. Setting: The Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto. Methods: Comprehensive clinicopathologic data were collected, including demography, clinical tumour staging (TNM), treatment, histopathologic details, recurrence, management, and follow-up. Main Outcome Measures: Local cancer control and disease-specific survival were the main outcome measures of interest. The Kaplan-Meier method was used to assess outcome measures by patient group, and the log-rank test was used to compare survival curves. Univariate and multivariate Cox proportional hazard regression analyses were used to test the association of various clinical factors and to identify independent prognostic factors of local control and disease-specific survival. Results: Sixty-five patients met inclusion criteria for our study (37 males; median age 64.4 years). Both local control and disease-specific survival were statistically significantly reduced in patients with positive intraoperative frozen section despite revision to obtain negative margins (p < .05). Multivariate analysis showed that microscopic tumour cut-through independently predicted poorer local control and disease-specific survival (p < .05). Conclusions: This study in patients receiving primary surgery for oral squamous cell carcinoma shows that microscopic tumour cut-through on intraoperative frozen section independently portends a poorer oncologic prognosis, regardless of ultimate tumour margin pathology.