Medical Care
Individualize the selection of treatment. [2] Base the treatment on factors related to ulcer disease, diarrhea, and malignant properties of the tumor. Antisecretory medications are helpful for controlling the manifestations of peptic acid disease and secretory diarrhea (secondary to hyperacidity).
Proton pump inhibitors (eg, omeprazole, lansoprazole)
These are highly effective drugs and are the drugs of choice for suppressing acid secretion. Long duration of action, fewer adverse effects, and high potency make them superior to H2 blockers.
In 60% of patients, ulcer healing occurs within 2 weeks. In 90-100% of patients, healing occurs within 4 weeks.
The recommended initial dose of omeprazole is 60 mg/d. Divided, twice-a-day dosing is suggested for doses greater than 80 mg/d. Once an effective maintenance dose is achieved, tapering of the medication, while monitoring symptoms and acid output, is suggested. [10]
H2-receptor antagonists
The dose usually is 4-8 times higher than the dose administered to patients with peptic ulcer disease.
Although a good success rate exists, this treatment has been reported to fail in 50% of patients.
Chemotherapy
This is indicated in patients with metastatic disease and in patients who are not candidates for surgery; however, it is not indicated for metastatic disease confined to the lymph nodes.
Chemotherapy reduces tumor size and improves the symptoms secondary to metastatic effects of the tumor.
A combination of streptozocin, 5-fluorouracil, and doxorubicin has been used, with the response rate reported to be as high as 65%.
Granberg et al described a patient with almost complete response to treatment with Sandostatin LAR, a long-acting somatostatin analog. [11]
Interferon or targeted radiotherapy may also be considered in patients who are not candidates for chemotherapy. Treatment of metastasized gastrinoma with targeted somatostatin-based radiotherapy with repeated cycles of 90yttrium-labeled tetraazacyclododecane-tetraacetic acid modified Tyr-octreotide ([90Y-DOTA]-TOC) or with cycles alternating between [90Y-DOTA]-TOC and 177lutetium-labeled DOTA-TOC ([177Lu-DOTA]-TOC) appears to improve the overall survival. [12, 13]
Consultations
Consult with the following specialists:
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Gastroenterologist
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Endocrinologist
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Oncologist
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Surgeon
Surgical Care
Surgical care is indicated for localized disease [14] ; resection is the treatment of choice for primary pancreatic neuroendocrine tumors (PNETs), because it is associated with increased survival. [2, 15] Indications for surgery include considerations of clinical symptom control, tumor size, location, extent, malignancy, and the presence of metastasis. [2]
Surgical resection of localized disease leads to a complete cure without any recurrence in 20-25% of patients with gastrinomas. The rate of recurrence-free survival is lower in patients whose symptoms do not improve following resection. [16]
The intraoperative use of a portable large field of view gamma camera (LFOVGC) and a handheld gamma detection probe (HGDP) may improve the localization and indium-111 (111In)-pentetreotide–radioguided gastrinoma resection and removal in patients with Zollinger-Ellison syndrome. [17]
Patients who have an isolated lesion or patients in whom the preoperative workup fails to localize the tumor should undergo laparotomy (by an experienced surgeon) with the intent to resect.
For patients with malignant pancreatic neuroendocrine tumors (PNETs), laparoscopy appears not to compromise oncologic resection and offers the advantages of reduced postoperative pain, improved cosmetic results, shorter hospital stay, and a shorter postoperative recovery period. [15]
It has been reported that Whipple pancreaticoduodenectomy affords the greatest probability for cure, particularly for multiple endocrine neoplasia type I (MEN I)-associated gastrinomas, although also for sporadic tumors, because it results in the removal of the entire gastrinoma triangle. However, the excellent long-term survival in patients with less complicated surgeries and the increased morbidity and mortality associated with the Whipple procedure make its general utility still unclear and it is recommended primarily for large, advanced tumors.
Long-Term Monitoring
Follow-up of patients with gastrinomas that have been resected is directed at the diagnosis and treatment of recurrence. Note the following:
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Measurement of the fasting serum gastrin level is the best screening test to monitor these patients.
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Disease recurrence might present as recurrent peptic ulceration, diarrhea, or abdominal pain.
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If recurrent disease is identified, reoperation may be considered and undertaken if no evidence of metastasis exists.
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Metastatic disease can be managed with chemotherapy and long-term acid suppression.
