The significance and indications for lymphadenectomy in pancreatic neuroendocrine neoplasms

BackgroundThe indication for lymphadenectomy in pancreatic neuroendocrine neoplasms (PNEN) remains unclear. Previous systematic reviews have reported varying frequencies of lymph node metastasis (LNM) based on tumor size, histopathological differentiation, and functionality. However, further stratification of LNM is needed for optimal lymphadenectomy. Thus, we addressed these issues with PNEN cases resected at our hospital.MethodsIn this study, we included 92 patients who underwent PNEN resection without distant metastasis between 1986 and December 2022. We retrospectively analyzed the risk factors of LNM, its stratification, and its prognosis.ResultsThe median age was 60 years, and 39 patients (42.4%) were female. Hereditary diseases included 8 with MEN-1 and 5 with VHL disease. Non-functional tumors (NF) accounted for 66 (71.7%), insulinomas for 17 (18.5%), gastrinomas for 5 (5.4%), glucagonomas for 2 (2.2%), and serotoninomas for 2 (2.2%). Pancreaticoduodenectomy (PD) was performed in 32 (34.8%), distal pancreatectomy (DP) in 41 (44.6%), total pancreatectomy (TP) in 4 (4.3%) and other procedures in 15 (16.3%). The distribution of Grade (G) 1/2/3 was 57 (61.9%)/32 (34.8%)/3 (3.3%), respectively. In multivariate analysis, the significant risk factors of LNM were gastrinomas (p=0.007), and tumor size > 2 cm (p=0.010). LNM was absent in 43 NF with tumors ≤ 2 cm. LNM were found in 3 NF with G1 larger than 5 cm. The overall 5-year and 10-year survival rates for patients with LNM were 81.5% and 71.3%, respectively, compared to 96.7% and 92.1% for those without LNM (p=0.049). The 5-year and 10-year recurrence-free survival rates were 78.8% and 67.5% for patients with LNM, versus 94.1% and 94.1% for those without LNM (p=0.002). Patients with LNM had significantly worse outcomes than those without LNM.ConclusionsLymphadenectomy might be unnecessary for NF or non-gastrinoma/glucagonoma G1 tumors that are smaller than 2 cm. These findings would suggest that the need for lymphadenectomy could be stratified based on tumor functionality, size, and grade. Further prospective studies are required to validate these findings.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.