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What is neuroendocrine cancer?

Neuroendocrine cancer is a malignant tumour that starts in neuroendocrine cells. Malignant means that it can spread, or metastasize, to other parts of the body.

Neuroendocrine cells are part of the diffuse neuroendocrine system. This system is a network of neuroendocrine cells throughout the body. Neuroendocrine cells are also in the endocrine system, which includes the pituitary, pineal, thyroid, parathyroid and adrenal glands, pancreatic islet cells (also known as islets of Langerhans) and the ovaries or testicles. Neuroendocrine cells have a structure similar to nerve cells, or neurons. They also make hormones like endocrine cells. They receive messages from the nervous system and make hormones in response to these messages. Neuroendocrine cells are present in different parts of the body, but they are mainly found in the digestive system and respiratory system.

Neuroendocrine cells can sometimes change and no longer grow or behave normally. These changes may lead to neuroendocrine tumours (NETs), which are abnormal growths that develop very slowly. Most often, NETs are non-cancerous, or benign.

Sometimes changes to neuroendocrine cells can cause cancer. There is also a small chance that non-cancerous NETs can become cancerous. These cancers are called malignant NETs, or neuroendocrine carcinomas.

Some tumours that develop in neuroendocrine cells make hormones. These are called functional tumours. Tumours that don’t make hormones are called non-functional tumours. Whether a tumour is functional or non-functional will affect the symptoms it causes and how it is treated.

Tumours that start in neuroendocrine cells occur most often in the digestive system. These include gastrointestinal (GI) and pancreatic NETs or carcinomas. NETs or carcinomas can also develop in the lung.

Other tumours can also develop in the neuroendocrine system, but they are rare. These include pheochromocytoma and paraganglioma. A rare genetic disorder called multiple neuroendocrine neoplasia (MEN) can also cause tumours in the neuroendocrine system.

You may hear the term carcinoid applied to NETs that are non-cancerous or that can become cancerous. It may also be used to describe neuroendocrine cancers in the stomach, intestine, appendix, rectum and lungs. Because this term can be confusing, experts recommended that it no longer be used to describe a neuroendocrine tumour.

Diagram of endocrine glands in the body


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