Prognostic Impact of Metastatic Site in Small Bowel Neuroendocrine Tumors

Document Type

Conference Proceeding

Publication Date

2-20-2026

Publication Title

Ann Surg Oncol

Keywords

biological marker, adult, aged, conference abstract, controlled study, distant metastasis, female, human, human tissue, major clinical study, male, metastasis, metastasis site, middle aged, overall survival, small intestinal neuroendocrine tumor, treatment outcome, tumor differentiation

Abstract

Small bowel neuroendocrine tumors (SBNETs) frequently present with distant metastases, yet the impact of metastatic site on survival remains poorly understood. There is currently no consensus on management strategies based on metastatic site, in part because it is unclear which sites most strongly influence patient outcomes. This study aims to evaluate the association between metastatic site and overall survival in SBNETs. METHODS : Patients diagnosed with SBNETs between 2004 - 2021 were identified from the National Cancer Database (NCDB). Patients were stratified according to metastatic site: no metastasis (NM), liver only metastasis (LM), lung only (LuM), bone only (BM), brain only (BrM), and distant lymph node only (dLN). Overall survival (OS) was estimated using Kaplan-Meier analysis and compared across metastatic sites. Subgroup analysis was performed by tumor differentiation (well vs. poorly differentiated). RESULTS: A total of 46,248 patients were included: 38,939 had NM, 6,838 had LM, 273 had dLN, 109 had BM, 79 had LuM, and 10 had BrM. Overall survival (OS) differed significantly by metastatic site (p < 0.001). Median OS was 161.8 months in NM, 114.3 months in LM, 69.5 months in BM, 54.3 months in LuM, 29.8 months in BrM, and was not reached in dLN. When stratified by tumor differentiation, well-differentiated tumors demonstrated markedly longer OS across all metastatic patterns. In well-differentiated SBNETs, median OS was 164.0 months (NM), 128.4months (LM), 81.6months (LuM), 29.8 months (BrM), and was not reached in dLN and BM groups. In contrast, among poorly differentiated SBNETs, survival was substantially worse. Due to limited sample size, analysis was restricted to NM and LM cohorts, with median OS of 42.8 months and 12.8 months, respectively. CONCLUSIONS: For patients with SBNETs, the site of metastasis is a significant determinant of OS. Among patients with metastatic disease, those with LM or dLN metastases experience the most favorable survival outcomes, followed by BM, while LuM and BrM are associated with the poorest prognosis. Tumor differentiation remains a powerful prognostic factor, with poorly differentiated tumors demonstrating significantly worse survival compared to well-differentiated tumors, even in non-metastatic patients. These findings emphasize the need to consider metastatic site in addition to tumor differentiation when risk stratifying patients and guiding management decisions.

Volume

33

Issue

1

First Page

S211

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