EP146 - Stage IV Small Bowel Neuroendocrine Tumors: Prognostic Factors and Long-Term Outcomes After Primary Tumor Resection

ePoster Presenter(s)

• 

  Francesca Roufael, MD

  Research fellow
  Department of colorectal surgery - Memorial Sloan Kettering Cancer Center
  Memorial Sloan Kettering Cancer Center
  New York, NY, United States

  Disclosure information not submitted.

Author(s)

• 

  Despoina Kanata, MD (she/her/hers)

  Research fellow
  Memorial Sloan Kettetring Cancer Center
  Memorial Sloan Kettering Cancer Center
  New York, NY, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.
• TG

  Tina Gowda, MD

  Research fellow
  Colorectal Surgery, Memorial Sloan kettering
  New York, New York, United States

  Disclosure information not submitted.
• MA

  Mohammad Ali Abbass, MD MPH

  Assistant Attending
  Memorial Sloan Kettering Cancer Center
  New York, New York, United States

  Disclosure information not submitted.
• 

  Georgios Karagkounis, MD

  Assistant Attending
  Memorial Sloan Kettering Cancer Center
  Memorial Sloan Kettering
  New York, NY, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no financial relationships with ineligible companies.
• 

  Maria Widmar, MD, MPH (she/her/hers)

  Assistant Attending
  Memorial Sloan Kettering Cancer Center
  Weill Cornell Medical Center
  New York, New York, United States

  All of the relevant financial relationships listed below have been mitigated.
  This individual has no relevant relationships with ineligible companies.
• IW

  Iris H. Wei, MD

  Assistant Attending
  Memorial Sloan Kettering Cancer Center
  New York, New York, United States

  Disclosure information not submitted.
• 

  Garrett M. M. Nash, MD, MPH

  Vice Chair of Quality and Safety
  Memorial Sloan Kettering Cancer Center
  New York, New York, United States

  Disclosure information not submitted.
• 

  Martin R. Weiser, MD

  Vice Chair for Faculty Affairs
  Memorial Sloan Kettering Cancer Center
  Cornell Medical College
  New York, New York, United States

  Disclosure information not submitted.
• 

  Philip B. B. Paty, MD

  Attending Surgeon
  Memorial Sloan Kettering Cancer Center
  New York, New York, United States

  Disclosure information not submitted.
• 

  Julio Garcia Aguilar

  Disclosure information not submitted.

Senior Author(s)

• 

  Emmanouil Pappou, MD, PhD

  Assistant Attending
  Memorial Sloan Kettering Cancer Center
  New York, New York, United States

  Disclosure information not submitted.

Purpose/Background: Small bowel neuroendocrine tumors (SB-NETs) are the most frequent primary malignancy of the small intestine and are often diagnosed at an advanced stage. Up to half of patients present with distant metastases, most frequently involving the liver and peritoneum. Although these tumors are typically indolent, outcomes in stage IV disease remain heterogeneous and poorly defined, particularly among those who undergo primary tumor resection. We aimed to describe clinicopathologic features, metastatic patterns, and outcomes after primary tumor resection for stage IV SB-NETs, and to identify predictors of progression and survival.

Methods/Interventions: We retrospectively reviewed consecutive patients with stage IV SB-NETs who underwent primary tumor resection at a tertiary cancer center between 2000 and 2023. Data included demographics, operative and pathologic characteristics, systemic therapies, and metastatic patterns. Overall survival (OS) and progression-free survival (PFS) were estimated with Kaplan-Meier methods, and Cox regression was used to evaluate prognostic factors.

Results/Outcomes: Sixty-eight patients were included. Median age was 60 years, 53% were female, and 68% had ileal primaries. Most tumors were well differentiated (73%) with frequent lymphovascular (93%) and perineural invasion (81%). Nodal metastases were present in 80% and tumor deposits in 61%. R0 resection was achieved in 92%. At baseline, 69% presented with hepatic metastases, 13% with extrahepatic, and 18% with multisite involvement. Over time, 93% developed liver metastases and 37% peritoneal spread, while bone metastases occurred in 22%. Somatostatin analogues were administered in 69%, radionuclide therapy in 18%, and cytotoxic chemotherapy in 6%.

Median OS was 140 months, with 5- and 10-year survival rates of 90% and 62%. Median PFS was 33 months, with 5-year PFS of 32%. Patients with ≥2 metastatic sites at baseline had significantly inferior OS (5-year 69% vs. 94%; HR 3.33, 95% CI 1.27-8.72, p=0.014) and shorter PFS (median 18 vs. 35 months). On multivariable analysis, older age (HR per 10 years 2.87, 95% CI 1.59-5.17, p< 0.001) and metastatic burden independently predicted worse OS, while Ki-67 ≥3% was associated with increased risk of progression (HR 1.97, 95% CI 1.02-3.83, p=0.044).

Conclusion/Discussion: In this single-institution cohort of surgically resected stage IV SB-NETs, long overall survival and moderate progression-free survival was observed. Survival outcomes varied by age, metastatic burden, and tumor biology, with worse prognosis in patients with multiple metastatic sites or higher Ki-67. These findings highlight prognostic factors within a selected group of surgically managed patients and provide contemporary benchmarks for survival in this setting, although limited by small sample size. Further studies including non-operated patients are needed to clarify the role of surgery in this setting.

Overall survival by baseline metastatic burden in patients with stage IV small bowel neuroendocrine tumors undergoing primary tumor resection
Kaplan-Meier curve showing overall survival (OS) stratified by number of metastatic sites at baseline (1 vs ≥2). Patients with ≥2 metastatic sites had significantly worse survival (5-year OS 69% vs 94%; log-rank p = 0.002).