Proton-pump inhibitors such as omeprazole. This group of medications suppress the acid secretion. H2-receptor antagonist similarly decrease acid secretion. Octreotide injections directly release somatostatin hormone that inhibits gastrin release. Chemotherapy. Prognosis
Patients with gastrinomas that are also known to be part of neuroendocrine neoplasms must have to deal with two factors related to this tumor. First, controlling the high amounts by using medications that inhibit gastrin levels. The second part is stabilizing the tumor progression. Gastrinomas have a rate of 60–90% that will become malignant. Patients who do not seek medical treatment such anti-ulcer medication have high rate of recurrence and death secondary to ulcer disease. The prognosis of gastrinoma depends on the level of metastases of the tumor. If patients present with hepatic metastases they might have remaining life span of one year with a five-year survival rate of 20–30%. In patients with localized tumor or localized lymph spread the survival rate of five years is 90%. Lastly, surgical resection of local tumor could lead to complete cure without recurrence in 20–25% of patients. Epidemiology
Gastrinoma is the second most common functional pancreatic neuroendocrine tumor (pNET), with a yearly incidence of approximately 0.5 to 21.5 cases per a million of people worldwide. Gastrinomas are located predominantly in the duodenum (70%) and pancreas (25%). Pancreatic gastrinomas are larger than their duodenal counterparts, may occur in any portion of the pancreas, and comprise 25% of these tumors. Gastrinomas are also the most common functional and malignant pancreatic endocrine tumors.
Diagnosis
In many cases, gastrinoma is diagnosed based on the patients history which is typically characterized by recurrent episodes of peptic ulcer disease or by severe reflux esophagitis and/or diarrhea or by acid-related symptoms which fail to respond to standard treatment regimens. To confirm the diagnosis of gastrinoma a series of blood tests must be made. One of those tests is the serum gastrin level, which is the most reliable test for patients with gastrinoma. The normal levels of gastrin are 150 pg/mL ( > 72.15 pmol/L); therefore elevated levels of > 1000 pg/mL (> 480 pmol/L) would establish the diagnosis of gastrinoma. Another test that can be conducted is the secretin stimulated test, which is useful in patients who have the sign and symptoms of gastrinoma but the gastrin levels are below < 1000 pg/mL. Usually, an Intravenous bolus consisting of secretin 2mcg/kg and is measured in 10 minute intervals up to 30 minutes total. Secretin, which is a hormone released from the duodenal S cells that induce the release of pancreatic bicarbonate (HCO3) that would neutralize the acidic environment due to high gastrin levels. Therefore, if the patients level of gastrin remains consistently high indicating gastrin release due to tumor such as gastrinoma.Other commonly used tests to further confirm the diagnosis are

CT scan of the abdominal area
Somatostatin receptor scintigraphy which is used to identify the location of the tumor
PET scan
Endoscopic ultrasound if there are no signs of tumor metastases. Treatment
Surgery is first line treatment in gastrinomas; however it often fails to be curative.