The pancreas is a gland about 6 inches long that is shaped like a thin pear lying on its side. The wider end of the pancreas is called the head, the middle section is called the body, and the narrow end is called the tail. The pancreas lies behind the stomach and in front of the spine Anatomy of the pancreas. The pancreas has three areas: head, body, and tail. It is found in the abdomen near the stomach, intestines, and other organs.
There are two kinds of cells in the pancreas:
- Endocrine pancreas cells make several kinds of hormones (chemicals that control the actions of certain cells or organs in the body), such as insulin to control blood sugar. They cluster together in many small groups (islets) throughout the pancreas. Endocrine pancreas cells are also called islet cells or islets of Langerhans.
- Exocrine pancreas cells make enzymes that are released into the small intestine to help the body digest food. Most of the pancreas is made of ducts with small sacs at the end of the ducts, which are lined with exocrine cells. This summary discusses islet cell tumors of the endocrine pancreas. See the PDQ summary on Pancreatic Cancer Treatment for information on exocrine pancreatic cancer.
A pancreatic neuroendocrine tumor (NET) may also be called a pancreatic endocrine tumor (PET), islet cell tumor, islet cell carcinoma, or pancreatic carcinoid.
Pancreatic NETs are much less common than pancreatic exocrine tumors and have a better prognosis.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, ifbreast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer
Pancreatic NETs may be functional (the hormones that are released cause symptoms) or nonfunctional(the hormones that are released do not cause symptoms) tumors:
- Functional tumors make one or more hormones, such as gastrin, insulin, and glucagon, that cause symptoms. Most functional tumors are benign (not cancer).
- Nonfunctional tumors make substances that do not cause symptoms. Symptoms are caused by the tumor as it spreads and grows. Most nonfunctional tumors are malignant (cancer).
Most pancreatic NETs are functional tumors.
There are different kinds of functional pancreatic NETs.
Pancreatic NETs make different kinds of hormones such as gastrin, insulin, and glucagon. Functional pancreatic NETs include the following:
Gastrinoma: A tumor that forms in cells that make gastrin. Gastrin is a hormone that causes the stomach to release an acid that helps digest food. Both gastrin and stomach acid are increased by gastrinomas. When increased stomach acid, stomach ulcers, and diarrhea are caused by a tumor that makes gastrin, it is called Zollinger-Ellison syndrome. A gastrinoma usually forms in the head of the pancreas and sometimes forms in the small intestine. Most gastrinomas are malignant (cancer).
Insulinoma: A tumor that forms in cells that make insulin. Insulin is a hormone that controls the amount of glucose (sugar) in the blood. It moves glucose into the cells, where it can be used by the body for energy. Insulinomas are usually slow-growing tumors that rarely spread. An insulinoma forms in the head, body, or tail of the pancreas. Insulinomas are usually benign (not cancer).
Glucagonoma: A tumor that forms in cells that make glucagon. Glucagon is a hormone that increases the amount of glucose in the blood. It causes the liver to break down glycogen. Too much glucagon causes hyperglycemia (high blood sugar). A glucagonoma usually forms in the tail of the pancreas. Most glucagonomas are malignant (cancer).
Other types of tumors: There are other rare types of functional pancreatic NETs that make hormones, including hormones that control the balance of sugar, salt, and water in the body. These tumors include:
- VIPomas, which make vasoactive intestinal peptide. VIPoma may also be called Verner-Morrison syndrome.
- Somatostatinomas, which make somatostatin.
These other types of tumors are grouped together because they are treated in much the same way.
Having certain syndromes can increase the risk of pancreatic NETs.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk with your doctor if you think you may be at risk.
Multiple endocrine neoplasia type 1 (MEN1) syndrome is a risk factor for pancreatic NETs.