Influence of perineural invasion on survival and recurrence in patients with resected pancreatic cancer.

BACKGROUND Perineural invasion (PNI) has been reported as one of the sources of locoregional recurrence in resected pancreatic cancer (PC). However the impact of PNI in resected pancreatic cancer remains controversial. The purpose of this study was to determine the association between PNI status and clinical outcomes. METHODS Publications were identified which assessed prognostic significance of PNI status in resected pancreatic cancer up to February 2013. A meta-analysis was performed to clarify the association between PNI status and clinical outcomes. RESULTS A total of 21 studies met the inclusion criteria, covering 4,459 cases. Analysis of these data showed that intrapancreatic PNI was correlated with reduced overall survival only in resected pancreatic ductal adenocarcinoma (PDAC) patients (HR=1.982, 95%CI: 1.526-2.574, p=0.000). Extrapancreatic PNI was correlated with reduced overall survival in all resected pancreatic cancer patients (HR=1.748, 95%CI: 1.372- 2.228, p=0.000). Moreover, intrapancreatic PNI status may be associated with tumor recurrence in all resected pancreatic cancer patients (HR=2.714, 95%CI: 1.885-3.906, p=0.000). CONCLUSION PNI was an independent and poor prognostic factor in resected PDAC patients. Moreover, intrapancreatic PNI status may be associated with tumor recurrence.