Prognostic Value and Clinical Predictors of Lymph Node Metastases in Pancreatic Neuroendocrine Tumors.

Objectives To investigate the correlation between lymph node metastasis (LNM) and various clinicopathological features of pancreatic neuroendocrine tumors (pNETs) and its impact on prognosis. Methods We searched the Surveillance Epidemiology and End Results database (2004-2015) for patients with surgically treated pNETs. Factors correlated with LNMs were analyzed by logistic regression and by Cox analysis. Results For tumors of 1 to 4 cm, age (P < 0.001, P = 0.014), grade (P < 0.001, P < 0.001), LNMs (P = 0.008, P < 0.001), and size (P = 0.038, P = 0.002) predicted overall survival (OS) and disease-specific survival (DSS). For tumor greater than 4 cm, age (P < 0.001, P = 0.001) and grade (P = 0.011, P = 0.048) were independent prognostic factors of OS and DSS. Lymph node metastasis modestly predicted DSS (P = 0.028) but not OS (P = 0.218). Conclusions In pNETs greater than 4 cm, LNM is not a predictor of OS and modestly predicts DSS, and lymphadenectomy may be unhelpful in these patients. For pNETs 1 to 4 cm, LNM predicts poor OS and DSS, which supports lymphadenectomy in these patients. Pancreas-sparing resection with only limited peripancreatic node sampling needs to be questioned.