Impact of Close Margins on Oral Cancer Outcomes According to the Oral Subsite

Background: The prognostic significance of close margins in oral squamous cell carcinoma (OSCC) is controversial. We wished to investigate the impact of close margins on the risk of local recurrence (LR) in OSCC according to the oral subsite. Methods: A retrospective cohort study of 342 OSCC patients undergoing primary surgical treatment was conducted. Surgical margins were based on the main specimen and defined as positive (SCC at margins), close (< 5 mm), or clear (≥ 5 mm). Results: Among tongue SCC cases, both positive (hazard ratio 13.48, 95% CI 2.03, 32.91) and close margins (hazard ratio 3.87, 95% CI 1.31, 11.34) were significantly associated with LR. Tongue margins < 4 mm were associated with higher LR. Among non-tongue SCC cases, only positive margins (hazard ratio 4.10, 95% CI 1.19, 14.21) were associated with LR. Close margins were not significant (hazard ratio 1.59, 95% CI 0.46, 5.42). Conclusions: Close margins appear to have a differential impact on LR in OSCC according to the oral subsite.