Stereotactic Body Radiation Therapy Facilitating Debulking Surgery in Metastatic VIPoma with Severe Diarrhea and Hypovolemic Shock

BACKGROUND Treatment of metastatic vasoactive intestinal peptide tumors (VIPoma) is challenging and requires a careful multidisciplinary approach to achieve optimal disease control. We present a case of metastatic VIPoma with recurring episodes of life-threatening diarrhea necessitating multiple intensive care unit (ICU) admissions. CASE REPORT A 54-year-old man presented with severe watery diarrhea and metabolic acidosis with MRI showing a necrotic pancreatic body mass, and multiple liver lesions. Histopathologic and biochemical findings were consistent with VIPoma. Due to the multifocal liver lesions, he was deemed unsuitable for curative surgical intervention, shifting focus to other therapies. Initial treatments over 7 months included octreotide, transarterial chemoembolization, yttrium-90 radioembolization, and systemic therapy with everolimus, with decreases in serum vasoactive intestinal peptide (VIP) levels from a peak of 3180 pg/mL to undetectable levels corresponding to temporary relief of diarrhea. However, the temporary relief was followed by a rapid increase in VIP levels into the 200s and 300s and recurrence of 3-11 liters of diarrhea per day. He had multiple ICU admissions due to severe diarrhea/hypovolemic shock until he was treated with stereotactic body radiation therapy (SBRT). SBRT of the pancreatic site immediately yielded long-term hemodynamic stability, prevented further ICU admissions, and enabled the patient to receive debulking surgery. CONCLUSIONS Although radiation is not typically a primary treatment modality for VIPoma, in this case, the high dose per fraction delivered with stereotactic technique to a pancreatic mass played a crucial role in alleviating his catastrophic volume loss through intravenous octreotide-refractory diarrhea, making the patient a suitable candidate for debulking surgery. This case highlights the importance of considering all available treatment options, even those not traditionally employed, when managing complex cases with refractory symptoms.