What are neuroendocrine tumours (NETs)?
Neuroendocrine tumours (NETs) start in cells of the neuroendocrine system. NETs can grow slowly (indolent) or grow quickly (aggressive). When NETs are aggressive, they can grow into and destroy nearby tissue. They can also spread (metastasize) to other parts of the body.
The neuroendocrine system is made up of neuroendocrine cells, which are spread throughout
the body. They are found in most organs in the body, including the
Neuroendocrine cells are like nerve cells (
Neuroendocrine cells sometimes change and no longer grow or behave normally. These changes may lead to NETs. Some NETs are found early before they spread. But sometimes changes to neuroendocrine cells can cause cancer and spread to other parts of the body. This type of cancer is called neuroendocrine carcinoma.
NETs are named and grouped according to where the tumour started in the body. NETs can
develop in organs of the GI tract, including the small intestine, rectum, stomach,
colon, esophagus and appendix. These types of tumours are called GI NETs. NETs can also
develop in the lungs (called lung NETs) or the
Other types of NETs can also develop. These include medullary thyroid cancer,
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