A lymph node ratio-based staging model is superior to the current staging system for pancreatic neuroendocrine tumors

Abstract

Context: The incidence of pancreatic neuroendocrine tumors (PNETs) is increasing. Current staging systems include nodal positivity, but the association of lymph node status and worse survival is controversial. Objective: The study aim was to determine the prognostic significance of lymph node ratio (LNR) and compare it with nodal positivity for PNET. Design, Setting, Participants, and Intervention: A retrospective analysis of the Surveillance, Epidemiology, and End Results database between 2004 and 2011 was performed in patients who underwent a pancreatectomy with lymphadenectomy. The primary outcome was disease-specific survival (DSS). Results: Of the 896 patients analyzed, T stage, N stage, distant metastasis, grade, extent of resection, sex, and age $57 years were significantly associated with worse DSS on univariate analysis. On multivariate analysis, age $57 [hazard ratio (HR) 1.75, 95% confidence interval (CI), 1.12 to 2.74, P = 0.015], male sex (HR 1.58; 95% CI, 1.01 to 2.48; P = 0.046), grade (poorly differentiated/ undifferentiated: HR 7.59; 95% CI, 4.71 to 12.23; P, 0.001), distant metastases (HR 2.45; 95% CI, 1.58 to 3.79; P, 0.001), and partial pancreatectomy (HR 2.55; 95% CI, 1.2 to 5.4; P = 0.015) were associated with worse DSS. Comparison between staging models constructed based on LNR cutoffs and the American Joint Committee on Cancer (AJCC) eighth edition staging system revealed that a model based on LNR $0.5 was superior. Conclusions: LNR $0.5 is independently associated with worse DSS. A staging system with LNR $0.5 was superior to the current AJCC eighth edition staging system.