Prognostic Value of Lymph Node Status and Extent of Lymphadenectomy in Pancreatic Neuroendocrine Tumors Confined To and Extending Beyond the Pancreas

Abstract

Background: The impact of lymph node (LN) status and lymphadenectomy (LA) on survival in pancreatic neuroendocrine tumors (pNETs) remains controversial. We evaluated the impact of tumor extension and grade on nodal metastasis and survival.

Methods: Surgical pNET patients were queried in the Surveillance Epidemiology and End Results (SEER) database (1998-2012, N = 981). Factors associated with LN status were analyzed by logistic regression and by Cox analyses.

Results: For T1-T2 tumors, N status was associated only with tumor size. N status (p = 0.001), grade (p < 0.001), age (p = 0.001), and sex (p = 0.007) predicted overall survival (OS). For T3-T4, grade (p < 0.001), sex (p = 0.004), size (p = 0.013), and age (p = 0.007) but not N status (p = 0.789) predicted OS. For T1-T2, disease-specific survival (DSS; p = 0.003) and OS (p = 0.008) were longer for N0 vs N1, while N0 vs NX had similar OS (p = 0.59) and DSS (p = 0.80). While a difference was seen in DSS for NX vs N1 (p = 0.04), no significant difference in OS was seen (p = 0.08). For T3-T4, N status did not affect DSS (p = 0.365) or OS (p = 0.454). For all T groups and any N status, extended LA (≥10 nodes resected) was not associated with OS.

Conclusion: While in T1-T2 pNET N1 status is a predictor of negative OS, similar outcome between NX and N0 supports limited LN resection in selected patients. Extended LA is unlikely to be helpful in T3-T4.

Keywords: Extend of lymphadenectomy; Lymph node metastasis; Lymph node status; Pancreatic neuroendocrine tumor; Prognostication; SEER; pNET.