Redefining Adequate Surgical Resection Margins for Oral Squamous Cell Carcinoma: Our Institutional Experience in 5 Consecutive Years

Background: Resection margin status is an important predictor of prognosis in patients with surgically treated OSCC. We introduced the concept of “adequate” versus "inadequate” resection margins. Methods: A sample of 87 consecutive patients who underwent surgical treatment for OSCC between 2014 and 2019 were retrospectively examined. Patient demographics, tumour characteristics, adjuvant therapy, recurrence status and patient survival (overall -OS- and disease-free -DFS) were evaluated. According to pathological findings, margins were considered clear (≥5 mm), close (1-5 mm) or involved (<1 mm). Using statistical analysis, a binomial cut-off point was established at 3 mm, and patients were classified into two groups according to primary tumour resection margins: “adequate” (margins ≥3 mm) and “inadequate” (margins <3 mm). Results: Clear surgical margins (≥5 mm) were reported in 72% tumour specimens, close in 12% and involved in 16%. Applying the 3 mm cutt-off, 21% patients were considered to have “inadequate” and 79% “adequate” resections. Adjuvant therapy was provided in 60% of cases, in accordance with Clinical Practice Guidelines. OS rate was 63% and DFS rate 64%. OS was significantly lower (p 0.05). Conclusions: An adequate surgical margin for OSCC could be defined at our institution by ≥3 mm, a close margin (≤2.99 mm) being an adverse risk factor in OSCC survival although further studies are needed to analyse the impact in terms of cancer recurrence rates.