The number of positive nodes accurately predicts recurrence after pancreaticoduodenectomy for nonfunctioning neuroendocrine neoplasms

Background: The most appropriate nodal staging for pancreatic neuroendocrine neoplasms (PanNENs) is unclear. Aim of the study was to evaluate the effect of the number of positive lymph nodes on prognosis after pancreaticoduodenectomy for PanNENs. Methods: A retrospective analysis of pancreaticoduodenectomies for nonfunctioning PanNENs was performed. PanNENs with nodal metastases (N+) were classified into N1 (1 to 3 positive lymph nodes) and N2 (4 or more positive lymph nodes). Univariate and multivariate analyses of disease-free survival were performed. Results: 157 patients were included. 99 patients (63%) had N0 PanNENs whereas 58 patients (37%) had nodal involvement (N+). Patients with N0 PanNENs had a 3-year disease-free survival rate of 89% compared with 83% and 75% in patients with N1 and N2 PanNENs, respectively (P < 0.0001). Independent predictors of disease-free survival were the presence of necrosis, lymph node ratio and nodal status. Factors positively correlated with the number of positive lymph nodes were the Ki67 value, the T stage and the number of examined lymph nodes. Similar percentage of N0 and N+ PanNENs was demonstrated for a cut-off of 13 examined lymph nodes. Conclusions: The number of positive lymph nodes is accurate in predicting recurrence for PanNENs. Thirteen examined lymph nodes seems to be the minimum number of lymph nodes to be resected/examined in patients who undergo pancreaticoduodenectomy for PanNENs.