32: Impact of Primary Tumor Resection on Metastatic Well-Differentiated Gastroenteropancreatic Neuroendocrine Tumors

Thursday, March 23, 2023

10:46 AM – 10:56 AM

Location: Ballroom A

Abstract Presenter(s)

Ashley Russo, MD

Complex General Surgical Oncology Fellow
Cedars-Sinai Medical Center - Los Angeles, CA
Los Angeles, California, United States

Disclosure(s): No financial relationships to disclose

First Author(s)

Ashley Russo, MD

Complex General Surgical Oncology Fellow
Cedars-Sinai Medical Center - Los Angeles, CA
Los Angeles, California, United States

Disclosure(s): No financial relationships to disclose

Author(s)

Timothy P. DiPeri, MD

T32 Research Fellow
The University of Texas MD Anderson Cancer Center
Houston, Texas, United States

Disclosure information not submitted.
JT

Joshua Tseng, MD

General Surgeon
Cedars-Sinai Medical Center - Los Angeles, CA, United States

Disclosure information not submitted.
CC

Courtney Chen, MD

General Surgery Resident
Cedars-Sinai Medical Center - Los Angeles, CA, United States

Disclosure information not submitted.
NN

Nicholas Nissen, MD

Director of Hepatobiliary and Pancreatic Surgery
Cedars-Sinai Medical Center - Los Angeles, CA, United States

Disclosure information not submitted.
FA

Farin Amersi, MD

Associate Professor of Surgery
Cedars Sinai Medical Center
Los Angeles , California, United States

Disclosure information not submitted.
AH

Andrew Hendifar, MD

Hematologist/Oncologist - Associate Professor of Medicine
Cedars-Sinai Medical Center - Los Angeles, CA, United States

Disclosure information not submitted.
Alexandra Gangi, MD

Assistant Professor Director, Gastrointestinal Tumor Program
Cedars Sinai Medical Center
Los Angeles, California, United States

Disclosure information not submitted.

Disclosure(s):

Ashley Russo, MD: No financial relationships to disclose

Introduction: Given the indolent nature of most gastroenteropancreatic (GEP) neuroendocrine tumors (NET), patients often present with advanced disease. Primary tumor resection (PTR) in the setting of unresectable metastatic disease is controversial but has been offered to select patients. Most studies evaluating the impact of PTR on overall survival (OS) in metastatic NET have been performed using large population-based databases, with limited treatment specific and progression data. This study aims to determine whether PTR improves OS and progression free survival (PFS) in patients with metastatic well-differentiated NET of the pancreas (PNET) and small bowel (SBNET).

Methods: This is a retrospective single institution study of patients who presented with metastatic well-differentiated PNET and SBNET between 1998-2021. The primary outcome was OS. The secondary outcome was PFS. Chi-squared tests and Cox regression were used to perform univariate and multivariate analyses (MVA). OS and PFS were estimated using the Kaplan-Meier method and log-rank test.

Results: 505 patients presented with metastatic NET between 1998-2021, 151 of whom met criteria of having metastatic, well-differentiated PNET (n=58) or SBNET (n=93). PTR was performed in 31 PNET (53.4%) and 77 SBNET (82.8%) patients. PTR improved median OS for both PNET (136 vs 61 months, p=0.003) and SBNET (not reached vs 79 months, p< 0.001). The majority of patients had metastatic liver disease (88.7%), 92/134 of whom underwent treatment of their liver metastases. Most patients who underwent PTR for SBNET did so in the setting of abdominal symptoms (68/77, 88.3%). The majority of patients in the metastatic PNET group who underwent PTR had a distal pancreatectomy (19/31, 61.3%). On MVA adjusted for demographics, primary site, PTR, grade, and treatment of liver metastases, only higher grade (HR 3.87, 95%CI 1.58-9.53) and PTR (HR 0.18, 95%CI 0.07-0.42) influenced OS. Treatment of liver metastases did not have a statistically significant impact on OS (HR 0.78, 95%CI 0.35-1.75). PTR resulted in longer median PFS for all patients (37 vs 23 months, p< 0.001) and patients with SBNET (46 vs 28 months, p=0.03), with a trend towards longer median PFS for patients with PNET (20 vs 13 months, p=0.07).

Conclusions: In patients with metastatic well-differentiated SBNET and PNET, PTR is associated with improved OS and PFS, regardless of treatment of liver metastases, and should be considered in a multidisciplinary setting. Future prospective studies are needed to validate these findings.

Learning Objectives:

Describe the impact of primary tumor resection on survival outcomes for patients with metastatic gastroenteropancreatic neuroendocrine tumors
Describe the cohort of patients with both metastatic small bowel and pancreatic neuroendocrine tumors who tend to undergo primary tumor resection
Describe the current limitations to answering the question of this study in a prospective manner