Prognostic Significance and Predictors of Nodal Recurrence After Surgery for Non-Functioning Pancreatic Neuroendocrine Tumors

Background: The prognosis of nodal recurrence after surgery for non-functioning pancreatic neuroendocrine tumors (NF-PanNETs) and its predictors have been poorly investigated. This study aimed to compare clinicopathologic features and survival between patients with nodal relapse and those with distant relapse and to identify predictors of nodal relapse after surgery for NF-PanNETs. Methods: All patients (n = 321) submitted to surgery for NF-PanNETs were included. Nodal recurrence was defined as the presence of one or more enlarged LNs at high-quality radiologic examinations and always confirmed by 68Ga-DOTA-PET or biopsy. Results: Altogether, 21 patients (6 %) experienced nodal (± distant) relapse, and 35 patients (11 %) had distant recurrence alone. Isolated nodal recurrence occurred for 23 % of patients with recurrence. Overall, 11 patients died of disease, one of whom (pT3N1G3) had an isolated nodal relapse. The rate of LN metastases (81 % vs 54 %; p = 0.044) and median number of positive LNs (PLN) (3 vs 0; p = 0.019) both were significantly higher for the patients with nodal (± distant) relapse than for those with distant relapse alone. Microvascular invasion (p = 0.046), T stage (p = 0.004), N stage (N1 [p = 0.049]; N2 [p = 0.001]), M stage (p < 0.001), and necrosis (p = 0.011) independently predicted nodal relapse. After distal pancreatectomy (n = 182), 13 patients experienced nodal recurrence, 9 of whom had left paraortic LNs involvement. Discussion: Lymph nodes are not rare sites of recurrence after surgery for NF-PanNETs. Lymph node involvement is a powerful determinant of nodal relapse. Nodal relapse frequently involves LNs that are not removed during standard lymphadenectomy.