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 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 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.