Characterization of Perineural Invasion Parameters for Risk Stratification in Oral Squamous Cell Carcinoma.

BACKGROUND: Perineural invasion (PNI) is an established adverse prognostic factor in oral squamous cell carcinoma (OSCC), but the implications of its extent as well as its relationship with surgical margin status and the extent of microscopic tumor spread remain unclear. METHODS: We retrospectively analyzed 165 patients with OSCC treated surgically with curative intent between 2010 and 2019. PNI was assessed for presence, subtype, number of foci, location, and diameter of the largest involved nerve. Associations with margin status and survival outcomes were evaluated using univariate and multivariate analyses. RESULTS: PNI was present in 29 patients (17.6%) and was associated with advanced tumor stage, nodal metastasis, positive surgical margins (HR 3.4, 95% CI 1.1-10.2), and increased use of adjuvant radiotherapy. While PNI presence predicted poorer survival, the diameter of the largest invaded nerve provided superior prognostic discrimination. A cutoff of 200 μm independently predicted disease-specific survival (HR 5.7, 95% CI 1.7-19.0) and significantly improved multivariable model performance. CONCLUSIONS: PNI correlates with positive surgical margins. Quantifying PNI, particularly nerve diameter, enhances prognostic stratification and may inform individualized surgical margin planning in OSCC.