A neuroendocrine tumour (NET) is a rare tumour that develops from cells of the neuroendocrine system. The neuroendocrine system is made up of cells that are similar to nerve cells and make chemical messengers called hormones. Hormones control how different organs in the body work.
Neuroendocrine cells are found throughout the body in organs such as the stomach, bowel and lungs.
NETs can be non-cancerous (benign) or cancerous (malignant). This information is about malignant tumours and is mainly about NETs affecting the digestive system.
NETs are classified according to where the cancer started (the primary tumour). For example:
- small bowel NETs
- large bowel NETs
- appendiceal NETs
- pancreatic NETs
- gastric NETs
- lung NETs.
Rarely, NETs occur in other areas, including the liver, gallbladder, bile ducts, kidneys, ovaries or testicles.
You may hear some NETs referred to as carcinoid tumours. These usually refer to tumours of the small bowel, large bowel or appendix.
NETs often grow slowly. It may be several years before symptoms appear and the tumour is diagnosed. However, some NETs are faster growing and more likely to spread to surrounding tissues and other parts of the body.