Pancreatic neuroendocrine tumors

Overview

Pancreatic neuroendocrine tumor (pNET) (also known as islet cell tumor) is a rare type of hormone-producing tumors that form in tissue of pancreas. The pancreas is a gland that is located in front of the spine and behind the stomach. It is a gland which plays a role in the digestive system by producing enzymes, which help to break down food as well as regulate blood sugar levels.

Pancreatic neuroendocrine tumor can be noncancerous (benign) or cancerous (malignant). Both types can result in major health issues. When pancreatic neuroendocrine tumor is cancerous, they are called pancreatic endocrine cancer (islet cell carcinoma).

Treatment option of pancreatic neuroendocrine tumors are surgery, peptide receptor radionuclide therapy, targeted therapy, radiofrequency ablation, and chemotherapy.

Classification of pancreatic neuroendocrine tumors

• Non-functional pancreatic NET: is a tumor that does not produce extra hormone and usually do not cause symptoms until they increase in size and out pressure on nearby tissue.
• Functional pancreatic NET: is a tumor that produce excessive amounts of hormones. The clinical manifestations depend on the hormone that it produces. Functional pancreatic NET includes the following:
  • Gastrinoma: is a tumor that develops in cells that produce gastrin. Gastrin is a hormone which is used in food digestion.
  • Insulinoma: is a tumor that produces an excessive amount of insulin, which cause hypoglycemia (low blood sugar).
  • Glucagonoma: is a tumor that produces an excessive amount of glucagon, which causes hyperglycemia (high blood sugar). The glucagon is a hormone that work with insulin to regulate the blood sugar level.

Symptoms

Non-functional pancreatic NET
The symptoms associated with this type depend solely on their size. The following are the signs and symptoms of this condition include:

• Jaundice (yellowish discoloration of the eyes and skin)
• Abdominal pain
• Diarrhea
• Nausea
• Loss of appetite
• Unexplained weight loss

Functional pancreatic NET
The symptoms depend on the hormone they produce. The following are signs and symptoms of this condition includes:

• Gastrinoma:
  • Abdominal pain
  • Heartburn
  • Diarrhea
• Insulinoma:
  • Hypoglycemia (low blood sugar)
  • Weakness and tiredness
  • An increase heartbeat
  • Confusion
  • Loss of consciousness
  • Blurred vision
• Glucagonoma:
  • Skin rash
  • Unexplained weight loss
  • Sore around the mouth
  • Passing a lot of urine
  • Diarrhea

Causes

Although most pancreatic neuroendocrine tumors (NETs) have an unknown specific cause, however researchers have identified many risk factors that can increase a person’s chance of developing this condition.

When hormone-producing islet cells in the pancreas undergo changes in their DNA, pancreatic neuroendocrine tumors develop. These instructions vary resulting in genetic mutations. The cells may start to multiply out of control and subsequently form a tumor, which is a collection of malignant cells.

Risk factors

The following factors have been linked to an increased risk of pancreatic neuroendocrine tumors:

• Gender - These tumors are significantly more common in male than in female.
• Family history – The risk is high if a family member has been diagnosed with a pancreatic neuroendocrine tumor.
• Inherited genetic syndromes – Some pancreatic NET may be linked to an inherited genetic syndrome such as:
  • Multiple endocrine neoplasia, type 1 (MEN 1) syndrome: MEN1 is a rare genetic disorder most often caused by a mutation in the MEN1 gene. This syndrome can affect parathyroid, pituitary gland, and the islet cells of the pancreas. These tumors typically develop early in life and are typically non-functioning pancreatic NET.
  • Von Hippel-Lindau disease: A small number of pancreatic NETs, which typically appear at younger ages (as low as 20 years old), are brought on by variations in the VHL gene. These tumors often slowly growing and are not functional.
  • Neurofibromatosis type1: also called Von Recklinghausen’s disease, is a genetic disorder caused by mutation in NF1 gene. People with this syndrome increase risk of pancreatic NET.