Perineural invasion as a prognostic factor in head and neck squamous cell carcinoma: a systematic review and meta-analysis.

Background: Squamous cell carcinoma (SCC) is the most common type of head and neck cancer, and head and neck squamous cell carcinoma (HNSCC) was proved to having a high prevalence of perineural invasion (PNI). Although some reports have revealed a relationship between PNI and the prognosis in HNSCC patients, the contribution of PNI to the prognosis remains unclear. Objectives: This study was aimed to comprehensively and quantitatively summarize the prognostic value of PNI for the survival of patients with HNSCC. Material and methods: We conducted PubMed and EMBASE to identify all relevant studies. A meta-analysis and subgroup analysis were performed to clarify the prognostic role of PNI. Results: A total of 18 studies (n = 3894) were included. 989 (25.4%) of the 3894 patients exhibited positive PNI, PNI was shown to be significantly associated with overall survival (OS) [hazard ratio (HR): 2.8, 95% confidence interval (CI): 1.88-4.16], disease-free survival (DFS) (HR = 2.42, 95% CI: 1.92-3.05) and disease-specific survival (DSS) (HR = 2.60, 95% CI: 1.86-3.63). Conclusions: The presence of PNI significantly affected OS, DFS and DSS in patients with HNSCC.