Validated Risk-Score Model Predicting Lymph Node Metastases in Patients with Non-Functiona Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND: The incidence of, and factors associated with, lymph node metastasis (LN+) in non-functional gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are not well characterized. METHODS: Patients were identified from the 2010-2015 National Cancer Database who underwent surgical resection with lymphadenectomy for clinical stage I-III non-functional GEP NETs. Among a randomly selected training subset of 75% of the study population, variables associated with LN+ were identified using multivariable logistic regression analysis, and these variables were used to create a risk-score model for LN+, which was internally validated among the remaining 25% of the cohort. RESULTS: Of 12,228 patients evaluated, 6,902 (56.4%) had LN+. Among the training set, variables associated with LN+ included age (70 years of age or older: odds ratio [OR] 1.12, 95% CI 1.00-1.24; ref: less than 70 years), tumor location (stomach: OR 3.72, 95% CI 2.94-4.71; small intestine: OR 19.60, 95% CI 17.31-22.19; ref: pancreas), tumor grade (moderately differentiated: OR 1.47, 95% CI 1.30-1.67; poorly differentiated/anaplastic: OR 1.53, 95% CI 1.21-1.95; ref: well-differentiated), tumor size (2-4 cm: OR 2.40, 95% CI 2.13-2.70; >4 cm: OR 5.25, 95% CI 4.47-6.17; ref: <2 cm), and lymphovascular invasion (OR 5.62, 95% CI 5.08-6.21; ref: no lymphovascular invasion). After internal validation, a risk-score model for LN+ using these variables was developed composed of low- (N = 2,779), intermediate- (N = 2,598), high- (N = 3,433), and very-high-risk (N = 3,418) groups; within each group the rate of LN+ was 8.7%, 48.6%, 64.9%, and 92.8%, respectively. CONCLUSIONS: This developed risk-score model, including both patient and tumor variables, can be used to calculate the risk for LN metastases in patients with GEP NETs. ((C) 2022 by the American College of Surgeons. Published by Wolters Kluwer Health, Inc. All rights reserved.)