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

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. This study was aimed to comprehensively and quantitatively summarize the prognostic value of PNI for the survival of patients with HNSCC. 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. A total of 18 studies ( = 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). The presence of PNI significantly affected OS, DFS and DSS in patients with HNSCC.