Impact of tumor size and nodal status on recurrence of nonfunctional pancreatic neuroendocrine tumors ≤2 cm after curative resection: A multi-institutional study of 392 cases

Background: The current study sought to define the impact of lymph node metastasis (LNM) relative to tumor size on tumor recurrence after curative resection for nonfunctional pancreatic neuroendocrine tumors (NF-pNETs) ≤2 cm. Methods: Patients who underwent curative resection for ≤2-cm NF-pNETs were identified from a multi-institutional database. Risk factors associated with tumor recurrence as well as LNM were identified. Recurrence-free survival (RFS) was compared among patients with or without LNM. Results: A total of 392 ≤2-cm NF-pNETs patients were identified. Among the 328 patients who had lymph node dissection and evaluation, 42 (12.8%) patients had LNM. LNM was associated with tumor recurrence (hazard ratio, 3.06; P =.026) after surgery. RFS was worse among LNM vs no LNM patients (5-year RFS, 81.7% vs 94.1%; P =.019). Patients with tumors measuring 1.5-2 cm had a two-fold increase in the incidence of LNM vs patients with tumors <1.5 cm (17.9% vs 8.7%, odds ratio, 2.59; P =.022), as well as a higher risk of advanced tumor grade and higher Ki-67 levels (both P <.01). After curative resection, a total of 14 (8.0%) patients with a tumor of 1.5-2 cm and 10 (4.5%) patients with tumor <1.5 cm developed tumor recurrence. Conclusion: Surgical resection with lymphadenectomy should be considered for patients with NF-pNETs ≥1.5-2.0 cm.