Neuroendocrine tumours (NETs) | Cancer Research UK
Cancer Research UK on Google+ Cancer Research UK on Facebook Cancer Research UK on Twitter

Neuroendocrine tumours (NETs)

This page tells you about neuroendocrine tumours. There is information about


The neuroendocrine system

The neuroendocrine system is made up of nerve and gland cells. It makes hormones and releases them into the bloodstream. Neuro means nerve and endocrine means the cells of the endocrine system. The endocrine system is a network of glands and organs in the body that produce hormones. It is also called the hormone system. Generally speaking, hormones control how our bodies work. This includes our growth and development, how we respond to changes such as stress, and many other things.

You can read about the hormone system in the about your body section.

There are neuroendocrine cells in most organs of the body.

Diagram showing the most common parts of the body for neuroendocrine tumours to develop

Neuroendocrine cells have different functions depending on where they are in the body. For example, the ones in the gut make hormones to control

  • The release of digestive juices into the gut
  • The muscles that move food through the bowel

Neuroendocrine cells in the lung release hormones that control the flow of air and blood in the lungs.


What neuroendocrine tumours are

Neuroendocrine tumours (NETs) are rare tumours that develop in cells of the neuroendocrine system. There are a number of different types of neuroendocrine tumour. The type you have depends on the particular cells that are affected.

Some NETs produce extra hormones and cause symptoms. These are called functioning tumours. Those that don’t produce extra hormones are called non functioning tumours.

Neuroendocrine tumours usually develop slowly over a number of years. Many people don’t have symptoms at first. And it is not unusual for people to find that a neuroendocine cancer has already spread to another part of the body when they are diagnosed.

There is some debate among doctors about how neuroendocrine tumours should be grouped and what they should be called. Although they develop from the same types of cell, they develop in different organs in the body. They also behave in different ways, for example some are slow growing while others are faster growing.

Neuroendocrine tumours may be non cancerous (benign) or cancerous (malignant). Generally speaking, benign neuroendocrine tumours tend to be slow growing and are low or intermediate grade. Neuroendocrine cancers tend to be faster growing and higher grade.

Other terms used for neuroendocrine tumours include

  • Gastroenteropancreatic neuroendocrine tumours (GEP NETs for short) – tumours in the gut or pancreas
  • Pancreatic neuroendocrine tumours (pNETs) – tumours that develop in the pancreas
  • Gastrointestinal neuroendocrine tumours (GI NETs) – tumours that develop in the bowel, stomach or food pipe (oesophagus)
  • Functioning neuroendocrine tumours (F-NETs)
  • Non functioning neuroendocrine tumours (NF-NETs)
  • Carcinoid tumour

The type of treatment you have depends on which type of NET you have and whether it has spread elsewhere in the body. Treatment may include surgery, chemotherapy, or drug treatment to control symptoms caused by the extra hormones.


Types of neuroendocrine tumour

There are a number of different types of NETs. They are generally called after the organ or type of cell they develop in.

NETs most often develop in the gut or pancreas. These tumours are sometimes grouped together and called gastroenteropancreatic neuroendocrine tumours or GEP NETs for short.

NETs of the gut are most often carcinoid tumours. They may also just be called carcinoid. There is a separate section about carcinoid tumours on this website.

NETs that develop in the pancreas are also called endocrine tumours of the pancreas. These are all rare types of tumour and include

  • Insulinomas, which produce insulin
  • Gastrinomas, which produce gastrin (a hormone that helps digest food)
  • Glucagonomas, which produce glucagon (a hormone that helps to raise blood sugar levels)
  • VIPomas, which produce vasoactive intestinal peptide (VIP for short) that helps digestion and a number of other body processes
  • Somatostatinoma, which produces the hormone somatostatin that helps with digestion

Some of these tumours can also develop outside the pancreas. For example, gastrinomas have been reported in the medical literature to develop in the ovaries, kidneys, stomach and liver, and not just in the pancreas and small bowel area.

NETs that develop in the lung are usually carcinoid tumours.

There are a number of other even rarer types of NET including those that develop in the


Risks and causes

Generally, the causes of NETs are unknown.

People who have one of the rare family syndromes have a higher risk of developing NETs. The family syndromes include

We also know from research that if one of your parents has had a NET your risk of developing it increases slightly. It is important to remember that they are rare tumours so even if your relative has a NET, your own risk is still very small.


More information about neuroendocrine tumours

You can find more information about the different types of neuroendocrine tumours by using the links below

Rate this page:
Submit rating


Rated 4 out of 5 based on 99 votes
Rate this page
Rate this page for no comments box
Please enter feedback to continue submitting
Send feedback
Question about cancer? Contact our information nurse team

No Error

Updated: 20 March 2014