Background: The objective of surgical management of oral squamous cell carcinoma (OSCC) is adequate resection with a clear margin. However, there is still a debate as to the optimal length for a mandibular resected margin.

Objective: To examine the length of peri-neural spreading in T4 mandibular invaded oral cavity squamous cell carcinoma.

Materials and Methods: Twenty-eight T4 pathological OSCC specimens that involved mandible and serial slices were studied and the length of tumor spreading along the inferior alveolar nerve (IAN) was determined. Tumor characteristics, risk factors, and survival were analyzed.

Results: The incidence of peri-neural invasion was 11.11%, and IAN invasion was found in 14.29% of the tumor-invaded mandibular marrow. The length of tumor spreading along IAN was 3 to 12 mm. Poor prognostic factors of T4 OSCC were it being located on the tongue (HR 14.16), was pathological N2-3 (HR 31.05), and had high-risk features such as peri-neural invasion, lymphovascular invasion, and extra-nodal extension.

Conclusion: A mandibular resected margin of at least 18 mm is recommended as a clear surgical margin in cases of T4 mandibular invasion OSCC.

Keywords: Oral cancer, Perineural invasion, Inferior alveolar nerve, Squamous cell carcinoma, Mandibulectomy

DOI: doi.org/10.35755/jmedassocthai.2020.05.

Received 30 Sep 2019 | Revised 5 Mar 2020 | Accepted 6 Mar 2020