Pancreatic neuroendocrine tumor | |
---|---|
Specialty | Oncology |
Treatment | Radiation, chemotherapy |
Prognosis | Five-year survival rate ~ 61% |
Pancreatic neuroendocrine tumours (PanNETs, PETs, or PNETs), often referred to as "islet cell tumours", [1] [2] or "pancreatic endocrine tumours" [3] [4] are neuroendocrine neoplasms that arise from cells of the endocrine (hormonal) and nervous system within the pancreas.
PanNETs are a type of neuroendocrine tumor, representing about one-third of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Many PanNETs are benign, while some are malignant. Aggressive PanNET tumors have traditionally been termed "islet cell carcinoma".
PanNETs are quite distinct from the usual form of pancreatic cancer, the majority of which are adenocarcinomas, which arises in the exocrine pancreas. Only 1 or 2% of clinically significant pancreas neoplasms are PanNETs. [5]
The majority of PanNETs are benign, while some are malignant. The World Health Organization (WHO) classification scheme places neuroendocrine tumors into three main categories, which emphasize the tumor grade rather than the anatomical origin. [3] In practice, those tumors termed well or intermediately differentiated PanNETs in the WHO scheme are sometimes called "islet cell tumors". The high-grade subtype termed neuroendocrine cancer (NEC) in the WHO scheme, is synonymous with "islet cell carcinoma".
Type | Relative incidence | Typical location of tumor [6] | Biomarkers [6] | Symptoms [7] |
---|---|---|---|---|
Insulinoma | 35–40% [7] | Head, body, tail of pancreas | insulin, proinsulin, C-peptide | Hypoglycemia |
Gastrinoma | 16–30% [7] | Gastrinoma triangle | gastrin, PP |
|
VIPoma | <10% [7] | Distal pancreas (body and tail) | VIP |
|
Somatostatinoma | <5% [7] | Pancreatoduodenal groove, ampullary, periampullary | somatostatin | |
PPoma | Head or pancreas | pancreatic polypeptide | ||
Glucagonoma | 1% [8] | Body and tail of pancreas | glucagon, glycentin |
Relative incidence is given as percentage of all functional pancreatic neuroendocrine tumors.
Some PanNETs do not cause any symptoms, in which case they may be discovered incidentally on a CT scan performed for a different purpose. [10] : 43–44 Symptoms such as abdominal or back pain or pressure, diarrhea, indigestion, or yellowing of the skin and whites of the eyes can arise from the effects of a larger PanNET tumor, either locally or at a metastasis. [11] [ medical citation needed ] About 40%[ medical citation needed ] of PanNETS have symptoms related to excessive secretion of hormones or active polypeptides and are accordingly labeled as "functional"; the symptoms reflect the type of hormone secreted, as discussed below. Up to 90% [12] of PanNETs are nonsecretory or nonfunctional, in which there is no secretion, or the quantity or type of products, such as pancreatic polypeptide (PPoma), chromogranin A, and neurotensin, do not cause a clinical syndrome although blood levels may be elevated. [13] In total, 85% of PanNETs have an elevated blood marker. [2]
Functional tumors are often classified by the hormone most strongly secreted, for example:
In these various types of functional tumors, the frequency of malignancy and the survival prognosis have been estimated dissimilarly, but a pertinent accessible summary is available. [17]
Because symptoms are non-specific, diagnosis is often delayed. [18]
Measurement of hormones including pancreatic polypeptide, gastrin, proinsulin, insulin, glucagon, and vasoactive intestinal peptide can determine if a tumor is causing hypersecretion. [18] [19]
Multiphase CT and MRI are the primary modalities for morphologic imaging of PNETs. While MRI is superior to CT for imaging, both of the primary tumor and evaluation of metastases, CT is more readily available. Notably, while many malignant lesions are hypodense in contrast-enhanced studies, the liver metastases of PNETs are hypervascular and readily visualized in the late arterial phase of the post-contrast CT study. However, morphological imaging alone is not sufficient for a definite diagnosis [18] [20]
On biopsy, immunohistochemistry is generally positive for chromogranin and synaptophysin. [21] Genetic testing thereof typically shows altered MEN1 and DAXX/ATRX. [21]
The new 2019 WHO classification and grading criteria for neuroendocrine tumors of the digestive system grades all the neuroendocrine tumors into three grades, based on their degree of cellular differentiation (from well-differentiated NET grade (G)1 to G3, and poorly-differentiated neuroendokrina cancer, NEC G3), morphology, mitotic rate and Ki-67 index. [22] The NCCN recommends the use of the same AJCC-UICC staging system as pancreatic adenocarcinoma. [10] : 52 Using this scheme, the stage by stage outcomes for PanNETs are dissimilar to pancreatic exocrine cancers. [23] A different TNM system for PanNETs has been proposed by The European Neuroendocrine Tumor Society. [24]
In general, treatment for PanNET encompasses the same array of options as other neuroendocrine tumors, as discussed in that main article. However, there are some specific differences, which are discussed here. [10]
In functioning PanNETs, octreotide is usually recommended prior to biopsy [10] : 21 or surgery [10] : 45 but is generally avoided in insulinomas to avoid profound hypoglycemia. [10] : 69
PanNETs in Multiple endocrine neoplasia type 1 are often multiple, and thus require different treatment and surveillance strategies. [10]
Some PanNETs are more responsive to chemotherapy than are gastroenteric carcinoid tumors. Several agents have shown activity. [16] In well differentiated PanNETs, chemotherapy is generally reserved for when there are no other treatment options. Combinations of several medicines have been used, such as doxorubicin with streptozocin and fluorouracil (5-FU) [16] and capecitabine with temozolomide.[ citation needed ] Although marginally effective in well-differentiated PETs, cisplatin with etoposide has some activity in poorly differentiated neuroendocrine cancers (PDNECs), [16] particularly if the PDNEC has an extremely high Ki-67 score of over 50%. [10] : 30
Several targeted therapy agents have been approved in PanNETs by the FDA based on improved progression-free survival (PFS):
Pancreatic neuroendocrine tumors may arise in the context of multiple endocrine neoplasia type 1, Von Hippel–Lindau disease, neurofibromatosis type 1 (NF-1) or tuberose sclerosis (TSC) [31] [32]
Analysis of somatic DNA mutations in well-differentiated pancreatic neuroendocrine tumors identified four important findings: [33] [7]
The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins and fats in food entering the duodenum from the stomach.
The pancreatic islets or islets of Langerhans are the regions of the pancreas that contain its endocrine (hormone-producing) cells, discovered in 1869 by German pathological anatomist Paul Langerhans. The pancreatic islets constitute 1–2% of the pancreas volume and receive 10–15% of its blood flow. The pancreatic islets are arranged in density routes throughout the human pancreas, and are important in the metabolism of glucose.
Multiple endocrine neoplasia is a condition which encompasses several distinct syndromes featuring tumors of endocrine glands, each with its own characteristic pattern. In some cases, the tumors are malignant, in others, benign. Benign or malignant tumors of nonendocrine tissues occur as components of some of these tumor syndromes.
Zollinger–Ellison syndrome is rare disease in which tumors cause the stomach to produce too much acid, resulting in peptic ulcers. Symptoms include abdominal pain and diarrhea.
Pancreatic cancer arises when cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a mass. These cancerous cells have the ability to invade other parts of the body. A number of types of pancreatic cancer are known.
Everolimus, sold under the brand name Afinitor among others, is a medication used as an immunosuppressant to prevent rejection of organ transplants and as a targeted therapy in the treatment of renal cell cancer and other tumours.
Glucagonoma is a very rare tumor of the alpha cells of the pancreas that results in the overproduction of the hormone glucagon. Typically associated with a rash called necrolytic migratory erythema, weight loss, and mild diabetes mellitus, most people with glucagonoma contract it spontaneously. However, about 10% of cases are associated with multiple endocrine neoplasia type 1 (MEN-1) syndrome.
An insulinoma is a tumour of the pancreas that is derived from beta cells and secretes insulin. It is a rare form of a neuroendocrine tumour. Most insulinomas are benign in that they grow exclusively at their origin within the pancreas, but a minority metastasize. Insulinomas are one of the functional pancreatic neuroendocrine tumour (PNET) group. In the Medical Subject Headings classification, insulinoma is the only subtype of "islet cell adenoma".
In medicine, a pancreatectomy is the surgical removal of all or part of the pancreas. Several types of pancreatectomy exist, including pancreaticoduodenectomy, distal pancreatectomy, segmental pancreatectomy, and total pancreatectomy. In total pancreatectomy, the gallbladder, distal stomach, a portion of the small intestine, associated lymph nodes and in certain cases the spleen are removed in addition to the entire pancreas. In recent years, the TP-IAT has also gained respectable traction within the medical community. These procedures are used in the management of several conditions involving the pancreas, such as benign pancreatic tumors, pancreatic cancer, and pancreatitis.
A carcinoid is a slow-growing type of neuroendocrine tumor originating in the cells of the neuroendocrine system. In some cases, metastasis may occur. Carcinoid tumors of the midgut are associated with carcinoid syndrome.
Multiple endocrine neoplasia type 1 (MEN-1) is one of a group of disorders, the multiple endocrine neoplasias, that affect the endocrine system through development of neoplastic lesions in pituitary, parathyroid gland and pancreas. Individuals suffering from this disorder are prone to developing multiple endocrine and nonendocrine tumors. It was first described by Paul Wermer in 1954.
Gastrinomas are neuroendocrine tumors (NETs), usually located in the duodenum or pancreas, that secrete gastrin and cause a clinical syndrome known as Zollinger–Ellison syndrome (ZES). A large number of gastrinomas develop in the pancreas or duodenum, with near-equal frequency, and approximately 10% arise as primary neoplasms in lymph nodes of the pancreaticoduodenal region.
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Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lung, and the rest of the body.
Somatostatinomas are a tumor of the delta cells of the endocrine pancreas that produces somatostatin. Increased levels of somatostatin inhibit pancreatic hormones and gastrointestinal hormones. Thus, somatostatinomas are associated with mild diabetes mellitus, steatorrhoea and gallstones, and achlorhydria. Somatostatinomas are commonly found in the head of pancreas. Only ten percent of somatostatinomas are functional tumours [9], and 60–70% of tumours are malignant. Nearly two-thirds of patients with malignant somatostatinomas will present with metastatic disease.
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A pancreatic tumor is an abnormal growth in the pancreas. In adults, almost 90% are pancreatic cancer and a few are benign. Pancreatic tumors are rare in children.
Mahvash disease is an autosomal recessive, hereditary pancreatic neuroendocrine tumor syndrome. The genetic defect that causes Mahvash disease is biallelic inactivating mutations of the glucagon receptor gene (GCGR). Mahvash disease was discovered by American physician Run Yu and his colleagues in 2008. Mahvash disease is very rare. There have been approximately 15 cases of Mahvash disease described in detail by the end of 2023. Mahvash disease occurs in both females and males. Mahvash disease is also called “glucagon cell hyperplasia and neoplasia” or “glucagon cell adenomatosis” by some authors but Mahvash disease is a distinct disease entity while the two alternative terms are mostly histological descriptions. Some patients with “glucagon cell hyperplasia and neoplasia” do not have glucagon receptor mutations.
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