Discrete Perineural Invasion Focus Number in Quantification for T1-T2 Oral Squamous Cell Carcinoma

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• Perineural invasion (PNI) is a known poor prognostic factor in early oral squamous cell carcinoma (OSCC).
• Current assessment of PNI is binary (present/absent), potentially missing crucial prognostic details.
• The clinical significance of varying PNI amounts in early OSCC warrants further investigation.

Purpose of the Study:

• To determine if quantifying PNI provides additional prognostic information for T1-T2 OSCC.
• To introduce and evaluate a novel parameter, the PNI focus number, for PNI quantification.
• To assess the correlation between PNI quantification and clinical outcomes such as lymph node metastasis and survival.

Main Methods:

• Retrospective cohort study of 314 patients with T1-T2 OSCC who underwent curative surgery.
• Pathologic reevaluation to define and quantify PNI using the 'PNI focus number'.
• Patients categorized into no PNI, low PNI (1-5 foci), and high PNI (>5 foci) groups for analysis of lymph node metastasis (LN+), 5-year disease-specific survival (DSS), and 5-year overall survival (OS).

Main Results:

• PNI focus number independently predicted LN+, poor DSS, and poor OS in multivariate analysis.
• A dose-dependent decrease in 5-year DSS was observed across groups: 88.6% (no PNI), 75.2% (low PNI), and 33.8% (high PNI).
• The high PNI group showed significantly worse 5-year DSS compared to the low PNI group.

Conclusions:

• The PNI focus number is a novel, valuable parameter for quantifying PNI in early OSCC.
• Quantification of PNI offers significant clinical insights beyond its presence or absence.
• Findings support the nerve-tumor interaction hypothesis and encourage further research into PNI-related treatment strategies for OSCC.