Evaluation of a new scoring system for assessing nerve invasion in resected pancreatic cancer: A single-center retrospective analysis

Nerve invasion (NI) is a characteristic feature of pancreatic cancer. Traditional dichotomous statements on the presence of NI are unreasonable because almost all cases exhibit NI when sufficient pathological sections are examined. The critical implications of NI in pancreatic cancer highlight the need for a more effective criterion. This study included 511 patients, who were categorized into a training group and a testing group at a ratio of 7:3. According to the traditional definition, NI was observed in 91.2 % of patients using five pathological slides in our study. The prevalence of NI increased as more pathological slides were used. The criterion of ‘two points of intraneural (endoneural) invasion in the case of four pathological slides’ has the highest receiver operating characteristic (ROC) score. Based on this new criterion, NI was proved to be an independent prognostic factor for overall survival (OS) and disease-free survival (DFS) and was also correlated with tumor recurrence (P = 0.004). Interestingly, gemcitabine-based chemotherapy regimen is an independent favorable factor for patients with high NI. In the high NI group, patients who received a gemcitabine-based regimen exhibited a better prognosis than those who did not receive the gemcitabine-based regimen for OS (P = 0.000) and DFS (P = 0.001). In conclusion, this study establishes assessment criteria to evaluate the severity of NI in order to predict patient outcomes.