Perineural Invasion in Squamous Cell Carcinoma of the Oral Cavity: Histology, Tumor Stage, and Outcome.

Abstract

To analyze the impact of different types of perineural invasion (PNI) in squamous cell carcinoma (SCC) of the oral cavity on overall survival and recurrence rate, with a special focus on histologic subtypes and tumor stage. Retrospective case-control study with clinicopathological analysis. Seventeen patients who received primary surgical treatment for SCC of the oral cavity with PNI were matched to a control group. In a histologic review, PNI was classified into subtypes according to an adapted Liebig classification. The term type A was used to describe tumor invasion into the nerve, whereas type B was used to describe circumferential growth around the nerve. Clinical charts were reviewed, and a Kaplan-Meier survival analysis was performed. The recurrence-free survival rates were 47.1% versus 80.4% (PNI vs. matched control group, P < 0.05), 60.0% versus 94.1% (PNI in stage I and II disease vs. matched control group, P < 0.05) and 41.7% versus 73.5% (PNI in stage III and IV disease vs. matched control group, P < 0.05). In most cases (n = 9) of PNI, both histologic subtypes (type A and type B) were present. Five cases exclusively showed type A, and three cases exclusively showed type B. Perineural invasion in early disease oral carcinoma has a particularly high impact on survival. Both histologic subtypes showed a significantly worse recurrence-free survival rate when compared to the control group. 3.