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ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Islet Cell Tumor. To see other pages, use the colored boxes on the right side of your screen. Think of those boxes as a roadmap to this full guide. Or, click “Next” at the bottom of each page.
About the pancreas
The pancreas is a pear-shaped gland located in the abdomen between the stomach and the spine. It is about six inches long and is composed of two major components:
Exocrine component. This component, which is made up of ducts and acini (small sacs on the end of the ducts), produces enzymes (specialized proteins) that are released into the small intestine to help the body digest and break down food, particularly fats.
Endocrine component. This part of the pancreas is made up of specialized cells clustered together in islands within the organ, called islets of Langerhans. These cells make specific hormones, specifically insulin (the substance that helps control the amount of sugar in the blood).
Types of pancreatic cancer
Cancer begins when normal cells change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body).
The most common type of pancreatic cancer is called ductal adenocarcinoma, or simply, adenocarcinoma. This type of pancreatic cancer begins in the exocrine component. Learn more about adenocarcinoma of the pancreas.
Much less commonly, tumors can begin in the islets of Langerhans, the endocrine component. An islet cell tumor can also be called a pancreatic islet cell tumor, pancreatic endocrine tumor, Islet of Langerhans tumor, or pancreatic neuroendocrine tumor. The rest of this section focuses on islet cell tumors.
Subtypes of islet cell tumors
An islet cell tumor can be either benign or cancerous. In addition, an islet cell tumor may be classified as either functioning or nonfunctioning. The cells in a functioning islet cell tumor produce hormones that cause specific symptoms, while a nonfunctioning islet cell tumor does not cause hormonal symptoms. Nonfunctioning tumors make up the majority of islet cell tumors. As a result, they are usually diagnosed at more advanced stages of disease.
There are five major classifications of functioning islet cell tumors based on the hormone the cells normally make. However, some tumors can make two or more of these hormones at the same time:
Gastrinoma. A gastrinoma is an islet cell tumor that makes too much gastrin, a hormone that causes acid production in the stomach, and can result in severe ulcers. This is a condition called Zollinger-Ellison syndrome.
Insulinoma. This type of tumor makes too much insulin, causing hypoglycemia (low blood sugar). An insulinoma is more likely to be noncancerous; only 10% become cancerous.
Glucagonoma. A glucagonoma is an islet cell tumor that makes too much of the hormone glucagon. Unlike an insulinoma, a glucagonoma causes hyperglycemia, a condition where there is too much sugar in the blood.
VIPoma. A VIPoma starts in the cells in the pancreas that make vasoactive intestinal peptide (VIP), a hormone that helps move water in the intestines. Too much VIP can cause chronic, watery diarrhea, which causes a condition called Verner-Morrison syndrome.
Somatostatinoma. A somatostatinoma usually develops in the head of the pancreas. A somatostatinoma may make somatostatin, a hormone that stops the secretion of several other hormones (such as growth hormone, insulin, and gastrin).
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