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What Are NETS?

NET Tumours  |  NET Cells  |  Formation  |  Medical History |  Can It Be Cured?


What are Neuroendocrine Tumors?

Neuroendocrine tumours (NETs) is the umbrella term for a group of unusual, often slow-growing cancers. These tumours develop from secretory cells found throughout the body and which are particularly concentrated in the gastrointestinal system, lung, pancreas, ovary and testes.These cells are referred to as the diffuse endocrine system to separate them from the discrete endocrine organs such as pituitary, thyroid, parathyroid and adrenal glands.





The term neuroendocrine implies that these cells have received some nervous connections (neuro-) and the cells have the ability to secrete hormones (endocrine).

Download your free copy of the Neuroendocrine tumours: A guide for patients and carers information booklet (PDF format).

Download your free copy of the Neuroendocrine tumours: A guide for healthcare professionals booklet (PDF format).




What are Neuroendocrine Cells?

The diffuse endocrine system is made up of neuroendocrine cells found in the respiratory and digestive tracts. These neuroendocrine cells have been also known as Kulchitsky cells, enterochromaffin cells or amine precursor uptake decarboxylase (APUD) cells.

Neuroendocrine cells are also located in the discrete endocrine glands of adrenals, pancreas, thyroid  and pituitary. These cells are also found in the ovaries and the testes.

NET cancers develop when these specialized cells undergo changes causing them to divide uncontrollably and grow into an abnormal tissue mass (tumour).

How are NET cancers formed?

The development of NETs is still not fully understood. As with all forms of cancer, NETs arise when cells multiply rapidly and in an abnormal way in the body.

Normally, all cells in the body replicate and grow in a tightly controlled manner. When this cell behaviour is disrupted, the cells divide and grow in an erratic and uncontrolled way. These cells are now behaving like a cancer cells. The cause for this change is not known, but increasing age, exposures to toxins (teratogens), a hereditary susceptibility can all play a part.  Most NETs occur without any hereditary link, but there are cases where NETs are present as part of a familial endocrine cancer syndrome such as MEN1, MEN 2, neurofibromatosis type 1 or Von Hippel Lindau.

Brief medical history of neuroendocrine cells

Neuroendocrine cells and were first described over a century ago and the term carcinoid was given to them in 1907 by Obendorfer. He described a tumour of the small intestine that grew much more slowly than normal cancers and erroneously classed it as ‘benign’. Unfortunately this misunderstanding still permeates throughout the medical community, worldwide. However, in the middle of the 20th century it became evident that these slow-growing tumours could be malignant and spread from the primary site to other parts of the body.

Today, the description carcinoid tumour is being slowly replaced in medical literature by the term NETs or gastroenteropancreatic tumours (GEPs). However, some doctors do still use the term carcinoid tumour or just carcinoid when they refer to NETs that develop in the stomach, duodenum, small intestine, appendix, colon or rectum.

Can NET cancers be cured?

When caught at an early stage, NET cancers can often be cured with surgery. As with all cancers, if a surgical cure is possible, this should be the first line of treatment. Patients must still be followed for at least ten years to ensure there is no recurrence of the cancer. Unfortunately, many patients are diagnosed later on, when the cancer has spread to other parts of the body. Even when the tumours have spread, the disease and its symptoms can often be controlled for many years. Please check our patient resources and fact sheets for more information.