Somatostatin releasing inhibitory tumor

　　Somatostatinoma is one of the rarest functional endocrine tumors, and its etiology is still under study.

　　1. Endocrine system:Somatostatin can significantly inhibit the release of endocrine hormones in the gastrointestinal system, especially in the pancreas, including insulin, glucagon, gastrin, motilin, secretin, cholecystokinin, pancreatic polypeptide, and vasoactive intestinal peptide. Whether it is normal tissue or tumor tissue, somatostatin can inhibit the release of the above peptide hormones through specific or receptor-mediated mechanisms.

　　2. Central nervous system:Inhibits the release of hypothalamic releasing hormones, such as growth hormone, thyrotropin, adrenocorticotropic hormone, and prolactin.

　　3. Gastrointestinal tract:Somatostatin can directly inhibit the secretion of gastric acid, gastric emptying, duodenal motility, biliary and gallbladder motility, exocrine pancreatic function, as well as the absorption of glucose, amino acids, and triglycerides. Somatostatin has paracrine effects on the gastrointestinal tract locally and plays a negative feedback regulatory role in the digestive and metabolic processes regulated by peptide substances.

　　1. Hypochlorhydria

　　Due to somatostatin inhibiting the secretion of gastrin and the acid secretion function of the stomach, all patients experience hypochlorhydria, with some even suffering from achlorhydria. The symptoms include indigestion and a feeling of fullness in the upper abdomen after eating.

　　2, Abdominal pain

　　The incidence of abdominal pain is about 35%, and the mechanisms include: malabsorption of nutrients; delayed gastrointestinal motility; tumor compression or secondary infection.

　　3, Gallstones

　　Between 26% and 65% of patients will develop gallstones, with about 16% of patients accompanied by jaundice of the skin and sclera. The possible causes of gallbladder stones may include: somatostatin inhibits the release of cholecystokinin; inhibits the motility of the bile duct and gallbladder; disorders in lipid metabolism.

　　4, Diarrhea

　　About 26% of patients with somatostatin-releasing inhibitory tumors have diarrhea, which is due to the absorption disorders of sugar, fat, and amino acids, leading to increased osmotic pressure in the feces; some patients may have steatorrhea. Approximately 19% of patients with somatostatin-releasing inhibitory tumors experience steatorrhea due to the decreased exocrine function of the pancreas, which leads to poor digestion and absorption of fats, thereby causing the disease.

　　5, Diabetes

　　The majority of patients with somatostatin-releasing inhibitory tumors will develop diabetes or decreased glucose tolerance, with severity ranging from mild elevation of blood sugar to significant diabetic ketoacidosis. The cause of diabetes is the secretion of a large amount of somatostatin by the tumor tissue, which inhibits the release of insulin; some patients, however, may have a significant reduction in the synthesis capacity of insulin due to the replacement of the pancreas by tumor tissue.

　　Due to the complex and diverse clinical manifestations of the disease, diagnosis is very difficult, especially early diagnosis. If the patient has symptoms of the triad of diabetes, gallstones, and steatorrhea, as well as symptoms such as dyspepsia, decreased gastric acid, weight loss, abdominal pain, or abdominal mass, the possibility of having a somatostatin-releasing inhibitory tumor should be considered. In combination with laboratory tests, gastrointestinal barium meal, duodenal hypotension contrast examination, B-ultrasound, CT, MRI examination, selective abdominal aortic angiography, and other localization examinations, the location of the tumor can be determined.

　　Clinical manifestations:Diabetes, decreased gastric acid, gallstones, abdominal pain, diarrhea,

　　In summary, the clinical manifestations of somatostatin-releasing inhibitory tumors are very complex and show diverse changes, and these symptoms are very common in the process of many other diseases. Some people call the simultaneous presence of diabetes, gallstones, and steatorrhea the 'triad' of somatostatin-releasing inhibitory tumors.

　　There are no specific preventive measures for this disease, mainly focused on early diagnosis and early treatment, and attention to hygiene and diet. Due to the complex and diverse clinical manifestations of the disease, diagnosis is very difficult, especially early diagnosis. If the patient has symptoms of the triad of diabetes, gallstones, and steatorrhea, as well as symptoms such as dyspepsia, decreased gastric acid, weight loss, abdominal pain, or abdominal mass, the possibility of having a somatostatin-releasing inhibitory tumor should be considered. In combination with laboratory tests, gastrointestinal barium meal, duodenal hypotension contrast examination, B-ultrasound, CT, MRI examination, selective abdominal aortic angiography, and other localization examinations, the location of the tumor can be determined.

　　First, laboratory examination

　　1. Gastric juice analysis:Insufficient gastric acid, even no gastric acid.

　　2. Elevated blood sugar or decreased glucose tolerance test.

　　3. Basal plasma somatostatin measurement:It is the main basis for the diagnosis of this disease. Any patient suspected of having somatostatinoma should have their level of somatostatin in plasma measured. In the morning on an empty stomach, the level of somatostatin in normal people is less than 100pg/ml, for somatostatinoma patients it is 0.16-107ng/ml, with an average of 15.5ng/ml, but a few patients may also have false-negative results.

　　4. Stimulation test:For patients suspected of having somatostatinoma in clinical practice, but whose level of somatostatin in plasma does not increase, the diagnosis can be further clarified through stimulation tests.

　　(1) Toluene sulfonamide (D860) stimulation test: After intravenous injection of toluene sulfonamide, the level of somatostatin in plasma can increase significantly in patients with tumor due to the stimulation of somatostatin release, but it does not increase in patients without tumor.

　　(2) Calcium pentapeptide gastrin test: After the patient with this disease is injected with calcium (calcium gluconate) and pentapeptide gastrin intravenously for 3 minutes, the level of somatostatin in plasma can increase by 2 times, and gradually return to normal after 10 minutes; for patients with somatostatinoma, whether pancreatic or extrapancreatic, with liver metastasis, the level of somatostatin in plasma is also significantly increased. This test does not increase the concentration of somatostatin in the plasma of normal people or patients with pancreatic adenocarcinoma.

　　Second, localization diagnosis

　　1. Gastrointestinal barium meal or duodenal hypotonic contrast examination:For tumors located in the descending segment of the duodenum or the head of the pancreas, there may be filling defects, enlargement of the duodenal loop, and indentation, but these changes are not helpful for tumors in the body or tail of the pancreas.

　　2. Ultrasound, CT or MRI examination:Since the tumor mass of this disease is usually large, it is often possible to find primary pancreatic tumors and liver metastatic tumors, with a high rate of localization diagnosis.

　　3. Selective abdominal aortic angiography:It can show the hemangioma of pancreatic tumor and its liver metastasis focus. The significance of localization diagnosis for this disease is similar to that of B-ultrasound, CT and MRI, with a diagnosis rate greater than 85%. However, these examinations can only determine the existence of the tumor, but cannot make a qualitative diagnosis.

　　1. Avoid overeating and excessive intake of cold drinks and cold foods.

　　2. Maintain smooth defecation. Constipation patients should eat foods rich in fiber and drink some honey every day.

　　3. Eat less refined rice and flour, and more refined rice, whole wheat bread, royal grain sugar, corn flour, yellow rice, beans (soybeans, lentils, snap beans, green peas) and other foods.

　　4. Often eat nutritious dried fruit and seed foods such as sunflower seeds, sesame seeds, pumpkin seeds, peanuts, raisins, etc. These foods contain a variety of vitamins, minerals, fiber, protein, and unsaturated fatty acids.

　　5. Meals should be regular, moderate, and eat less and more often. Plan to intake sufficient calories and nutrition. Eating less and more often is more suitable for patients with digestive tract cancer.

　　6. Eat more foods rich in vitamin A and vitamin C, and eat more green vegetables and fruits.

　　7. Often eat foods containing inhibitory effects on carcinogenesis, such as turnips, cabbage, and shepherd's purse.

　　8. Do not eat salted and smoked foods, especially charred and carbonized foods.

　　9. Adhere to a low-fat diet and eat more lean meat, eggs, and yogurt.

　　10. Food should be as fresh as possible, and moldy or deteriorated food should not be eaten.

　　First, Surgical Treatment

　　Surgical treatment is the preferred method for the treatment of somatostatinoma. However, due to the high rate of metastasis in patients with this disease, the rate of surgical resection is not very high. Moreover, because most patients have large tumors, it is often not suitable to perform tumor excision; therefore, pancreatectomy is the main surgical treatment effect.

　　1. For tumors in the body and tail of the pancreas, a resection of the body and tail of the pancreas can be performed.

　　2. For tumors located in the head of the pancreas, a subtotal pancreatectomy or pancreato-duodenectomy should be performed.

　　3. For giant tumors or liver metastatic tumors that cannot be removed by radical resection, palliative reductive surgery can often achieve the purpose of alleviating symptoms and extending life.

　　Second, Internal Medicine Treatment

　　For patients with advanced tumors who have no surgical conditions, comprehensive internal medicine treatment measures can be adopted. However, due to the small number of cases, the evaluation of specific chemotherapy measures and their effects is affected to a certain extent. In a group of 4 patients treated with simple internal medicine, 1 patient was treated with streptozotocin alone, which could partially alleviate symptoms and survive for 5 years. In another group of 3 patients, 2 were treated with streptozotocin plus 5-Fu, and their symptoms improved significantly; another patient was treated with doxorubicin alone, which could also partially alleviate symptoms. The overall survival rate of the two groups of patients was 48% at 1 year and 13% at 5 years.