How Rare Are Pancreatic Neuroendocrine Tumors? Symptoms, Causes

What are pancreatic neuroendocrine tumors?

Pancreatic neuroendocrine tumors (pNET), also called islet cell tumors or pancreatic neuroendocrine neoplasms (pNEN), are a type of pancreatic tumors that arise from the hormone-producing cells (called islet cells) in the pancreas. They could be noncancerous (benign) or cancerous (malignant). The exact nature of the tumor can only be found on biopsy.

• The pancreas is an organ present in your abdomen behind the stomach. It is shaped like a flattened pear and is almost the size of your hand (about six inches long and less than two inches wide). It has three parts: the head, body, and tail.
• The pancreas plays important role in digestion and produces certain hormones. Hormones are produced by the islet cells of the pancreas. The two main hormones, called insulin and glucagon, produced by the pancreas play a crucial role in glucose metabolism and, thus, regulation of blood sugar levels in the body.

Because pancreatic neuroendocrine tumors arise from the endocrine cells of the pancreas, they may secrete pancreatic hormones. Pancreatic neuroendocrine tumors that produce hormones are called functional tumors, whereas those that do not produce hormones are called nonfunctional tumors.

Most pancreatic neuroendocrine tumors are nonfunctional and do not give rise to any hormone-related symptoms.

5 classifications of pancreatic neuroendocrine tumors

Functional pancreatic neuroendocrine tumors may be further classified depending on the hormone they produce:

1. Gastrinoma: These tumors produce the hormone gastrin. This hormone increases stomach acid secretion. Most gastrinomas are malignant (cancerous).
2. Insulinoma: These tumors produce insulin hormone. Insulin helps lower blood glucose levels. Most insulinomas are benign (noncancerous).
3. Glucagonoma: These tumors produce glucagon hormone that helps increase blood glucose levels. Most glucaganomas are cancerous.
4. Somaostatinoma: These tumors produce the hormone called somatostatin. This hormone lowers the formation of some other hormones, such as insulin, growth hormone, and gastrin. Most somatostatinomas are cancerous.
5. VIPoma: These tumors produce the hormone called vasoactive intestinal polypeptide or VIP. This hormone increases watery secretions from the gut. Most VIPomas are cancerous.

What are the symptoms of pancreatic neuroendocrine tumors?

The symptoms of pancreatic neuroendocrine tumors may vary depending on various factors, such as whether they are functional or non-functional, the size of the primary tumor, and how far they have spread (metastasized) in the body.

The symptoms may include:

• Nonfunctional pancreatic neuroendocrine tumors: Because these tumors do not cause hormone-related symptoms, they are generally diagnosed incidentally or when the tumor grows large enough to press on adjacent structures or when it has metastasized to other sites in the body. They may cause symptoms, such as:
• Functional pancreatic neuroendocrine tumors: The symptoms of these tumors may vary depending on the hormones that they mainly produce.
  • Gastrinoma
  • Insulinoma
  • Glucagonoma
  • VIPoma
  • Somatostatinoma

What causes pancreatic neuroendocrine tumors?

The exact cause of pancreatic neuroendocrine tumors is unknown. These tumors arise when cells in the endocrine part of the pancreas grow out of control. There are no known environmental or lifestyle factors that may cause them.

Certain inherited conditions, however, may be associated with these tumors. They include multiple endocrine neoplasia type I (MEN1), neurofibromatosis type I (NF-1), tuberous sclerosis, and von Hippel-Lindau syndrome (VHL).

Pancreatic neuroendocrine tumors are more common in males than in females. Having a family history of pancreatic neuroendocrine tumors may increase your risk of having these tumors.

How are pancreatic neuroendocrine tumors treated?

Treatment of pancreatic neuroendocrine tumors depends on factors, such as:

• Type of tumor
• Location
• Size
• The extent of the tumor (whether it has spread or not)
• General health and preferences of the patient

Discuss with your doctor which treatment plan will work best for you. Treatment options may include: