Overview

The pancreas is a pear-shaped gland located in the abdomen, between the stomach and the spine. It is about six inches in length and is made up of two major components: exocrine cells and endocrine cells. The exocrine component, made up of ducts and acini (small sacs on the end of the ducts), produces enzymes, which are specialized proteins released into the small intestine that help the body digest and break down food. It is the cells lining these pancreatic ducts that most frequently become cancerous. This is called ductal adenocarcinoma of the pancreas and represents the most common subtype of pancreatic cancer; for more information, read the Cancer.Net Guide to Pancreatic Cancer.

The endocrine component of the pancreas is made up of specialized cells clustered together in islands within the organ, called islets of Langerhans. These cells produce hormones, the most critical one being insulin, an important substance that helps regulate the amount of sugar in the blood. Rarely, a tumor will form in these islet cells. An islet cell tumor can also be called a pancreatic islet cell tumor, pancreatic endocrine tumor, Islet of Langerhans tumor, or neuroendocrine tumor. An islet cell tumor can be benign (noncancerous) or malignant (cancerous), meaning it has the ability to spread to other parts of the body.

An islet cell tumor may be either functioning or nonfunctioning. There are five major classifications of functioning islet cell tumors:

Gastrinoma. A gastrinoma describes an islet cell tumor that produces a large amount of gastrin, a hormone that causes an excess amount of acid to be made in the stomach. This results in a condition called Zollinger-Ellison syndrome.

Insulinoma. This type of tumor produces too much insulin, resulting in hypoglycemia (low blood sugar). An insulinoma is more likely to be benign; only 10% become malignant.

Glucagonoma. A glucagonoma is an islet cell tumor that produces too much of the hormone glucagon. In contrast to an insulinoma, a glucagonoma causes hyperglycemia, a condition where there is too much sugar in the blood.

VIPoma. A VIPoma arises from cells in the pancreas that produce vasoactive intestinal peptide (VIP), a hormone that plays a role in water transport in the intestines. Excessive amounts of VIP can cause chronic, watery diarrhea, which causes a condition called Verner-Morrison syndrome.

Somatostatinoma. A somatostatinoma is a tumor that usually develops in the head of the pancreas. A somatostatinoma may produce somatostatin, a hormone that inhibits the secretion of several other hormones (such as growth hormone, insulin, and gastrin).

There is one major classification of nonfunctioning islet cell tumors:

Nonfunctioning tumors. Nonfunctioning tumors make up the majority of islet cell tumors. They produce none of the clinical syndromes seen above and, as a result, they are typically diagnosed at more advanced stages of disease.

Statistics

Islet cell tumors are uncommon yet highly treatable, with 200 to 1,000 new cases diagnosed each year in the United States.

Cancer statistics should be interpreted with caution. Estimates are based on data from multiple cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with an islet cell tumor.

Source: National Cancer Institute

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