Perineural Invasion/lymphovascular Invasion Double Positive Predicts Distant Metastasis and Poor Survival in T3-4 Oral Squamous Cell Carcinoma

Postoperative adjuvant therapy has been indicated by advanced T classification for T3-4 oral squamous cell carcinoma (OSCC) and the significance of perineural invasion (PNI) and lymphovascular invasion (LVI) in treatment for T3-4 OSCC remains unclear. Ninety-eight cumulative patients with T3-4 OSCC who underwent curative surgery between Jan 2002 and Dec 2010 were recruited and analyzed. Twenty-seven (27.6%) patients were PNI/LVI double positive. PNI/LVI double positive demonstrated independent predictive values for higher neck metastasis (LN+), higher distant metastasis (DM) and low 5-year disease-specific survival (DSS) rates (p < 0.001, p = 0.017, and p < 0.001, respectively) after controlling for other pathologic features of the primary tumors. A high DM rate of 33.3% was noted in PNI/LVI double-positive patients. Among the PNI/LVI double negative, single positive to double positive subgroups, increasing LN+, DM rates and decreasing DSS rate were observed. Among the 44 LN+ patients, PNI/LVI double positive remained associated with a markedly high DM rate of 42.9% and a poor 5-year DSS of 27.7%. PNI/LVI double positive plays important roles in prognostication and potential clinical application for T3-4 OSCC by independently predicting LN+, DM, and poor DSS, and can be used as a good marker to select DM high-risk patients for novel adjuvant therapy trials.