Prognostic impact of perineural invasion in oral cancer: a systematic review

INTRODUCTION: Numerous studies have evaluated the prognostic significance of perineural invasion (PNI) in oral cancer; however, the results are inconclusive. PURPOSE: To identify the prognostic value of PNI in oral cancer through a metanalysis. METHODS: A literature review was carried out, searching the MedLine databases via Pubmed, Scielo, Lilacs, Cochrane and Websco. RESULTS: A total of 56 studies were included. The results indicate that PNI in oral cancer has an incidence of 28% (95% confidence interval (CI) 24-31%); 5-year survival with relative risk (RR) 0.67 (0.59-0.75); 5-year disease-free survival RR 0.71 (0.68-0.75); locoregional recurrence with RR 2.09 (1.86-2.35). CONCLUSIONS: PNI is a negative prognostic factor in oral cancer.