Neuroendocrine Tumor of the Pancreas: Introduction

Approved by the Cancer.Net Editorial Board, 08/2017

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 Neuroendocrine Tumor of the Pancreas. Use the menu to see other pages. Think of that menu as a roadmap for this complete guide.

About the pancreas

The pancreas is a pear-shaped gland located in the abdomen between the stomach and the spine. It is about 6 inches long and is made up of 2 major components:

  • Exocrine component. This component is made up of ducts with small sacs called acini at the end. It produces specialized proteins called enzymes 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 hormones, specifically insulin. Insulin is the substance that helps control the amount of sugar in the blood.

About pancreatic cancer

Cancer begins when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.

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, a tumor can develop in the islets of Langerhans, the endocrine component. These tumors may be referred to as pancreatic neuroendocrine tumors, pancreatic neuroendocrine tumors, pancreatic endocrine tumors, islet of Langerhans tumors, or pancreatic neuroendocrine tumors. The rest of this section focuses on neuroendocrine tumors in the pancreas.

Subtypes of pancreatic neuroendocrine tumors

A pancreatic neuroendocrine tumor can be either benign or cancerous. A pancreatic neuroendocrine tumor may also be classified as either functioning or nonfunctioning. The cells in a functioning pancreatic neuroendocrine tumor produce hormones that cause specific symptoms. A nonfunctioning pancreatic neuroendocrine tumor does not cause hormonal symptoms. Most pancreatic neuroendocrine tumors are nonfunctioning. Because of a lack of symptoms, these tumors are usually diagnosed at a more advanced stage.

There are 5 major classifications of functioning pancreatic neuroendocrine tumors. These types are based on the hormone that the cells normally make. However, some tumors can make 2 or more of these hormones at the same time.

  • Gastrinoma. A gastrinoma is a pancreatic neuroendocrine tumor that makes too much gastrin, a hormone that causes acid production in the stomach. Too much stomach acid can cause severe ulcers, a condition called Zollinger-Ellison syndrome.

  • Insulinoma. This type of tumor makes too much insulin, causing hypoglycemia, also known as low blood sugar. An insulinoma is more likely to be noncancerous. Only 10% become cancerous.

  • Glucagonoma. A glucagonoma is a pancreatic neuroendocrine 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 into 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 a hormone called somatostatin. This hormone stops the production of several other hormones, such as growth hormone, insulin, and gastrin.

The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with this type of tumor and general survival rates. You may use the menu to choose a different section to read in this guide.