Patterns and prognostic predictive value of perineural invasion in esophageal squamous cell carcinoma

BACKGROUND: The pathological phenotype of perineural invasion (PNI) in squamous cell carcinoma (ESCC) is prevalent but highly heterogeneous. METHODS: Postoperative specimens from all patients with ESCC at Shaanxi Provincial People’s Hospital were evaluated for PNI using haematoxylin and eosin (H&E) staining and S100 immunohistochemistry (IHC). We determined the correlation between PNI status and clinical outcomes. RESULTS: Among 349 ESCC cases, PNI was identified in 127 patients (36.3%), and four subtypes of PNI were identified in our study. Correlation analysis confirmed that PNI was related to tumour invasion depth (pT stage) and lymph node status (pN stage) (P < 0.05). Multivariate analysis showed that PNI (P = 0.001) was an independent factor affecting disease-free survival (DFS) in ESCC, and a similar result was found for overall survival (OS) (P = 0.017). Further analysis revealed that PNI status was a prognostic factor of DFS (P < 0.001) and OS (P = 0.003) exclusively in pN-negative patients. We also found that patients with the PNI-a subtype had better DFS (P = 0.002) and OS (P = 0.002) than patients with the other three subtypes (PNI-b, c, d). CONCLUSION: The pathological phenotypes of PNI are diverse, and the identification of PNI subtypes has important clinical guiding value.