Perineural invasion correlates with postoperative distant metastasis and poor overall survival in patients with PT1-3N0M0 esophageal squamous cell carcinoma

The aim of this study was to determine the prognostic value of perineural invasion (PNI) in patients with PT1-3N0M0 esophageal squamous cell carcinoma (ESCC) who underwent curative resection. A total of 148 patients with PT1-3N0M0 ESCC, who underwent surgery in Zhejiang Cancer Hospital (Hangzhou, People's Republic of China), between 2006 and 2009, were evaluated in this retrospective study. The effects of PNI on distant metastasis-free survival (DMFS) and overall survival (OS) were assessed using Kaplan-Meier analysis. Independent prognostic factors were identified by multivariate Cox analysis. Positive PNI was identified in 25.0% of all the cases. The depth of invasion (PT stage) was closely associated with the PNI positivity (P<0.001). The 5-year DMFS rate and OS rate of the PNI-positive patients were significantly worse than those of the PNI-negative patients (DMFS: 37.2% vs 62.3%, P=0.009; OS: 31.3% vs 74.3%, P<0.001). Multivariate analysis indicated that the positivity of PNI was an independent prognostic factor for both DMFS (hazard ratio [HR] =2.35, P=0.039) and OS (HR =3.56, P=0.002). Our results suggest that PNI was a predictor of distant metastasis and independently associated with prognosis of patients with PT1-3N0M0 ESCC.