Lymph node ratio, but not the total number of examined lymph nodes or lymph node metastasis, is a predictor of overall survival for pancreatic neuroendocrine neoplasms after surgical resection.

Peng Liu,Brigitte Vollmar,Lili Lu,Min Sun,Xianbin Zhang,Zhaohui Tang,Fei Cao,Yuru Shang,Peng Gong

doi:10.18632/oncotarget.19184

Abstract

AimTo evaluate the prognostic significance of lymph node metastasis, extent of examined lymph nodes (ELNs) and lymph node ratio (LNR) for resected pancreatic neuroendocrine neoplasms (pNENs).Materials and MethodsSurgically resected pNENs were assimilated from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier and Cox proportional hazard models were used to examine the prognostic effect of clinicopathological characteristics on overall survival; Harrell’s concordance index was performed to assess the prognostic accuracy of all independent prognostic factors; and the Spearman’s rank correlation was used to assess the correlation between LNR and other clinicopathological characteristics.ResultsTotally, 1,273 pathologically confirmed pNENs were included in our study. The extent of ELNs failed to show any survival benefit in entire cohort (ELNs ≤ 12 vs. ELNs > 12, P = 0.072) or pNENs without lymph node metastasis (ELNs ≤ 28 vs. ELNs > 28, P = 0.108). Lymph node metastasis and LNR > 0.40 were significantly (both P < 0.001) adverse prognostic factors of overall survival. However, only LNR > 0.40 was the independent predictor of survival after adjusted for other clinicopathological characteristics. Besides LNR, the age, gender, primary tumor site, grade and stage also were the independent predictors of overall survival; and this survival model had an acceptable predictive power (Harrell’s concordance index, 0.731).ConclusionsThe current study suggested that the LNR, not the total number of ELNs and the lymph node metastasis, is an independent prognostic indicator of overall survival for pNENs after surgical resection.

Highlights

Pancreatic neuroendocrine neoplasms, known as pancreatic endocrine tumors, islet cell neoplasms or islet cell carcinomas, are rare tumors with an annual incidence of 0.19/100,000–0.32/100,000 [1,2,3]
Besides lymph node ratio (LNR), the age, gender, primary tumor site, grade and stage were the independent predictors of overall survival; and this survival model had an acceptable predictive power (Harrell’s concordance index, 0.731)
The current study suggested that the LNR, not the total number of examined lymph nodes (ELNs) and the lymph node metastasis, is an independent prognostic indicator of overall survival for Pancreatic neuroendocrine neoplasms (pNENs) after surgical resection

Summary

Introduction

Pancreatic neuroendocrine neoplasms (pNENs), known as pancreatic endocrine tumors, islet cell neoplasms or islet cell carcinomas, are rare tumors with an annual incidence of 0.19/100,000–0.32/100,000 [1,2,3]. Lymph node metastasis is commonly used as a critical prognostic factor for predicting survival and disease progression of pancreatic ductal adenocarcinomas (PDAC) and pNENs [6,7,8,9]. Some studies showed that lymph node metastasis was not an independent prognostic factor of PDAC and pNENs [10, 11]. The accuracy of staging lymph node was directly proportional to the number of examined lymph nodes (ELNs), and many studies suggested that the extent of ELNs was significantly associated with survival of PDAC, especially in patients without lymph node metastasis [12,13,14]. Lymph node ratio (LNR), the number of metastatic lymph nodes divided by the total number of ELNs, was increasingly recognized as a more powerful prognostic factor than lymph node metastasis in PDAC [10, 11, 15], intraductal papillary mucinous [16], and ampullary carcinoma [17, 18]

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