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Hormonal and Rare Conditions Neuroendocrine Tumors Gastroenteropancreatic neuroendocrine tumours (GEP-NETs)
Gastroenteropancreatic neuroendocrine tumours (GEP-NETs)
About GEP-NETS

Gastroenteropancreatic neuroendocrine tumours (GEP-NETs)

GEP-NETS are a rare form of tumour that develops in the gastroenteropancreatic (GEP) system, which includes the pancreas and digestive system.

GEP-NETS are tumours that derive from neuroendocrine cells.1 These are cells that are similar to nerve cells but can also produce hormones that control many body functions. 

  • The term neuro refers to nerve signalling and response.2
  • The term endocrine refers to making and releasing hormones.2 

These cells can sometimes change, which causes them to stop behaving normally and can lead to the development of a neuroendocrine tumour (NET).3

Neuroendocrine cells are found throughout the body in almost all organs. But neuroendocrine tumours (NETs) typically develop in:2,3

An infographic with a person in the centre with arrows pointing to different body parts that NETS develop in, as follows. Thyroid or parathyroid, Lungs (around 20% of neuroendocrine cancers start in the lung), adrenal gland, and pituitary gland. Two other arrows point to the pancreas and the digestive system (around 40% of neuroendocrine cancers start in the digestive system). Together these two systems form the gastroenteropancreatic (GEP) system. The digestive system includes the oesophagus/food pipe, stomach, small intestine, appendix, colon, and rectum.

There are also neuroendocrine cells in the kidneys, liver, prostate, skin, cervix, ovaries, and testicles.3

When a NET is in the gastroenteropancreatic (GEP) system it is known as a GEP-NET; so GEP-NETs are neuroendocrine tumours (NETs) that appear in the digestive tract or the pancreas.

GEP-NETs are a complex part of medicine, because every case is different:2,3

  • Some tumours may cause no symptoms
  • Some tumours can release extra hormones that can cause different symptoms
  • Some GEP-NETs grow quickly, while others grow more slowly
  • The effects of a GEP-NET can vary a lot depending on where it originated
  • Other health conditions can cause the same symptoms as NETs

How many people have GEP-NETs?

In 100,000 people, on average you would expect to find between 2 and 5 people with GEP-NETS4

This means that GEP-NETs are classed as a rare disease

Unfortunately, as GEP-NETs are so rare, there isn’t a lot of information about the condition, so it’s hard to give exact numbers.

What we do know is:

  • Less than 1% of new cancer diagnoses are for GEP-NETs (about 0.5%)5
  • The number of people with GEP-NETs is growing. This might be because:4-7
    • More people are getting the condition
    • Awareness of GEP-NETs is growing
    • Doctors are getting better all the time at testing for and diagnosing GEP-NETs

References

  1. Díez M, Teulé A, Salazar R. Gastroenteropancreatic neuroendocrine tumors: diagnosis and treatment. Ann Gastroenterol. 2013;26(1):29-36.
  2. CRUK. What are NETs? Available at: https://www.cancerresearchuk.org/about-cancer/neuroendocrine-tumours-nets/what-are-nets. Last accessed April 2025.
  3. Canadian Cancer Society. The Neuroendocrine system. Available at: https://cancer.ca/en/cancer-information/cancer-types/neuroendocrine. Last accessed April 2025.
  4. Kizilgul M, Delibasi T. Review article: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Transl Gastrointest Cancer 2015;4(1):39-56.
  5. Oronsky B et al. Nothing but NET: A review of Neuroendocrine Tumors and Carcinomas. Neoplasia 2017;19(12):991-1002.
  6. Dasari A et al. Trends in the Incidence, Prevalence, and Survival Outcomes in Patients With Neuroendocrine Tumors in the United States. JAMA Oncol 2017 1;3(10):1335-1342.
  7. Chauhan A et al. Global burden of neuroendocrine tumors and changing incidence in Kentucky. OncoTarget 2018;9(27).