Redefining adequate margins in oral squamous cell carcinoma: outcomes from close and positive margins

Purpose Adequacy of surgical margins impacts outcomes in oral cancer. We sought to determine whether close and positive margins have different outcomes in patients with oral cancer. Methods Retrospective data from 612 patients with oral carcinoma were analyzed for the effect of margin status on locoregional recurrence-free survival (LRFS), disease-free survival (DFS) and overall survival (OS). Results A total of 90 cases (14.7%) had close margins and 26 patients (4.2%) had positive margins. Recurrences were documented in 173 patients (28%), of which 137 (22% of the study sample) were locoregional, and 164 patients (27%) had died. Among patients with close or positive margins, a cutoff of 1 mm optimally separated LRFS (adjusted p = 0.0190) and OS curves (adjusted p = 0.0168) whereas a cutoff of 2 mm was sufficient to significantly separate DFS curves (adjusted p = 0.0281). Conclusions Patients with oral carcinoma with positive margins (< 1 mm) had poorer outcomes compared to those with close margins (1–5 mm) in terms of LRFS, DFS and OS. There is a suggestion that a cutoff of < 2 mm might provide slightly more separation for DFS.