EFFECTIVE MEDICAL THERAPY FOR MULTIPLE ENDOCRINE NEOPLASIA TYPE 1-ASSOCIATED METASTATIC VIPoma

Abstract

INTRODUCTION/BACKGROUND
Pancreatic islet cell tumors occur in 40% of MEN 1 patients. VIPoma is a rare functioning pancreatic neuroendocrine tumor characterized by excessive secretion of vasoactive intestinal peptide (VIP), with an annual incidence of fewer than 1 in 10 million in the general population. Most cases are sporadic, but about 5% are linked to multiple endocrine neoplasia type 1 (MEN 1) syndrome. We describe a patient with MEN 1-associated metastatic VIPoma.

CASE
A 56-year-old female was first diagnosed with a benign insulinoma in 2005 and underwent successful laparoscopic tumor excision. There was no prior or family history of endocrine tumors. In 2019, she developed intermittent abdominal pain and chronic diarrhea which progressed over a 3-year period.

In 2022, investigations confirmed elevated vasoactive intestinal peptide (VIP) levels of 276 pg/mL (normal reference: <75 pg/mL) and a pancreatic body tumor with diffuse pancreatic infiltration, as well as liver and nodal metastases were identified on multimodal imaging. Extensive debulking surgery was recommended, but the patient declined.

In March 2023, she presented to our hospital with hypovolemic shock resulting from profuse diarrhea and severe hypokalemia. Intramuscular octreotide long-acting release (LAR) 30 mg was initiated, leading to prompt symptom control, and she continued to receive monthly injections. Genetic studies confirmed multiple endocrine neoplasia type 1 (MEN 1), prompting subsequent screening of family members.

By March 2024, the patient was asymptomatic, had experienced significant weight gain (from 50 to 65 kg), and her VIP levels had normalized to 66 pg/mL. A Gallium-68 (Ga-68) DOTATATE PET/CT scan in March 2024 demonstrated stable pancreatic and nodal disease but progressive liver metastases. The neuroendocrine multidisciplinary team offered the option of peptide receptor radionuclide therapy (PRRT), but she declined this treatment.

CONCLUSION
This case highlights the effectiveness of medical management with Octreotide LAR for control of symptoms and tumor-related hormonal hypersecretion in inoperable metastatic VIPoma regardless of disease progression. A personalized multidisciplinary approach is a pre-requisite for achieving optimal outcomes.