Overview

Function of the pancreas

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 composed of two major components:

• The exocrine component, 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.
  
  
• 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 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 begin to 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 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. Also, an islet cell tumor may be classified as either functioning or nonfunctioning. The term functioning means that the tumor cells produce hormones that cause specific symptoms, while a nonfunctioning islet cell tumor does not produce hormones.

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 a lot of gastrin, a hormone that causes too much acid in the stomach. This causes 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 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).

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 symptoms or syndromes described above. As a result, they are usually diagnosed at more advanced stages of disease.

Find out more about basic terms used in this section.