The number of positive lymph node is a better predictor of survival than the lymph node metastasis status for pancreatic neuroendocrine neoplasms: A retrospective cohort study.

BACKGROUND: The recently released AJCC TNM staging system of pancreatic adenocarcinoma has endorsed the number of positive lymph node(NPLN) as the criterion of N staging. However, the prognostic role of NPLN is still unclear for pancreatic neuroendocrine neoplasms (pNENs).

METHODS: Patients underwent resection and at least one lymph node examined were identified from the Surveillance, Epidemiology, and End Results database. The overall survival (OS) and disease specific survival (DSS) were estimated using Kaplan-Meier analysis and compared by log-rank test. The prognostic factors were determined by cox proportional regression model.

RESULTS: Totally, 1,269 pNENs were included in the present study. The increasing NPLN (NPLN > 3) was corresponding significantly (P < 0.05) shorter OS and DSS in both entire cohort (OS: NPLN ≤ 3 vs. NPLN > 3, 93.624 ± 1.765 months vs. 75.075 ± 4.005 months; DSS: NPLN ≤ 3 vs. NPLN > 3, 104.829 ± 1.455 months vs. 85.443 ± 3.938 months, respectively) and cohort with the number of examined lymph node more than 11 (OS: NPLN ≤ 3 vs. NPLN > 3, 88.759 ± 2.756 months vs. 73.664 ± 4.700 months; DSS: NPLN ≤ 3 vs. NPLN > 3, 99.021 ± 2.212 months vs. 85.139 ± 4.686 months, respectively). Furthermore, the multivariate analysis showed the NPLN > 3 rather than lymph node status was the independent prognostic factors for OS and DSS in these two cohorts.

CONCLUSIONS: The NPLN seems more meaningful than the lymph node metastasis status as prognostic factor for survival. Taking into account the prognostic value of NPLN for pNENs might improve the current TNM staging systems. However, prospective study is needed to demonstrate our findings.