Prognostic value of neural invasion for resectable pancreatic ductal adenocarcinoma

Background Neural invasion(NI) is a typical characteristic of pancreatic ductal adenocarcinoma (PDAC), which accounts for 90% of intrapancreatic NI and cannot serve as a prognostic indicator for patients with poor prognosis. This study aimed to explore the prognostic value of NI in PDAC through detailed analysis of intrapancreatic NIand extrapancreatic perineural invasion(EPNI). Methods Patients who underwent radical pancreatectomy for PDAC between July 2018 and December 2022 were enrolled and divided into training and internal test groups. Binary classification, numeration, and NI severity scores were applied to describe the status of intrapancreatic NI, and EPNI was diagnosed on CT. Cox regression analysis was performed to determine the parameters associated with poor prognosis in the training group and were validated in the internal test group. Results Among 195 patients, the overall detection rates of intrapancreatic NI and EPNI were 97.4% and 42%, respectively. EPNI( p =0.01), pathological stage of nodes of grade 2( p =0.001), and NI severity score( p =0.04) were responsible for shorter recurrence-free survival(RFS). Meanwhile, increased age ( p =0.009), EPNI( p =0.001), pathological stage of nodes was grade 2( p =0.003), poor tumor differentiation ( p =0.022), and NI severity score( p =0.032) had significant prognostic impacts on overall survival(OS).Further analysis indicated 10.5 points of an NI severity score was the cut-off value to define patients with different prognoses. Kaplan-Meier survival curves demonstrated that NI severity scores greater than 10.5 points were associated with poor RFS(10 vs.24 months, p =0.001) and OS(19 vs. 27 months, p =0.001). Similarly, EPNI was associated with shorter RFS(8 vs. 18.5 months, p =0.001) and OS(17 vs. 25 months, p =0.001). These results were validated in the internal test group. In addition, NI severity scores greater than 10.5 points were related to early recurrence within 6 months after pancreatectomy. Conclusions EPNI and NI severity scores greater than 10.5 points are important prognostic indicators and can serve as predictors for tumor recurrence after detailed pathological assessment.