Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (also called islet cell tumors or pancreatic NETs) are rare tumors that start in your pancreas’ endocrine cells. Your pancreas is a flat pear-shaped gland tucked beside your stomach and small bowel. Endocrine cells in your pancreas make hormones that manage digestion and blood sugar levels. A pancreatic NET may affect your digestive system or your blood sugar levels.

Pancreatic neuroendocrine tumors can be cancerous or noncancerous.

How common are pancreatic neuroendocrine tumors?

They’re rare. The most recent data estimates that 5 in 1 million people develop a type of pancreatic neuroendocrine tumor.

Types of pancreatic neuroendocrine tumors

Healthcare providers classify pancreatic neuroendocrine tumors as being functioning or nonfunctioning:

• Functioning pancreatic NETs may release excessive amounts of hormones, the chemicals that carry messages throughout your body that tell it what to do and when to do it.
• Nonfunctioning pancreatic NETs don’t release hormones, but they can cause issues if they grow large enough to press on nearby organs, like your belly.

There are several types of pancreatic NETs, each with different characteristics. Some but not all of them are cancerous, meaning they can spread from your pancreas to other parts of your body. Some cause other conditions or have links to other conditions. All the tumors below are functioning pancreatic NETs.

Pancreatic neuroendocrine tumor types are:

• Insulinomas. This is the most common type of functional pancreatic NET, accounting for about 70% of all pancreatic neuroendocrine tumors. Most insulinomas are benign (noncancerous.) Insulinomas affect the cells that release insulin, the hormone that keeps your blood sugar from getting too high.
• Gastrinomas. About 50% of gastrinomas are cancerous. This tumor affects the cells that release gastrin, which triggers your stomach to produce gastric acid. Too much gastric acid in your stomach causes ulcers, acid reflux and other issues.
• Glucagonomas. Glucagonomas are slow-growing tumors that usually are cancerous. They affect the cells that release glucagon, the hormone that keeps your blood sugar from getting too low.
• VIPomas. VIP stands for “vasoactive intestinal peptide,” a hormone that relaxes the muscles in your stomach and bowels and manages the balance of sugar, salt and water in your digestive tract.
• Somatostatinomas. These are slow-growing cancerous tumors. They affect the cells that release somatostatin. About 10% of people with somatostatinomas develop somatostatinoma syndrome, which increases their risk of diabetes and/or gallstones.