This retrospective review from Japan assessed 89 patients who underwent surgery for squamous cell carcinoma of the tongue, specifically they reviewed the evidence of perineural and vascular invasion (27.0% and 23.6%). Their results suggest, not unsurprisingly, that perineural and vascular invasion are effective predictors of regional metastases.
Furthermore, they concluded that perineural invasion may be a clinical predictor of survival.
The five year survival of stage I and stage II disease with these factors was significantly lower than those without. They advocate elective neck dissection in clinical stage I and II cases when perineural or vascular invasion is found.