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Neuroendocrine Tumors

  • Amy Scholten, MPH
Publication Type:


Neuroendocrine Tumors


Neuroendocrine tumors (NETs) are a rare type of tumor that can make hormones. Hormones are usually made and released by the neuroendocrine system. This system is made up of special tissues and glands. The endocrine tissue is partially controlled by the brain. Hormones affect how the body works. Examples are the metabolic rate, blood flow, or breathing. They can also change the levels of materials in the blood, such as glucose or calcium.

NETs are found throughout the body in the cells of the:

In many cases, neuroendocrine tumors cannot be identified as a specific type of cancer. When this happens, it is called neuroendocrine carcinoma.

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Cancer is when cells in the body split without control or order. These cells go on to form a growth or tumor. Cancer refers to harmful growths. These growths attack nearby tissues and can spread to other parts of the body. It is not clear exactly what causes these problems. It is likely a mix of genes and the environment.

Risk Factors

The risk of NETs depend on the type of cancer. The risk is higher in those who:

  • Eat a diet high in saturated fat—GI tract
  • Smoke—lungs
  • Spend excess amounts of time in the sun—skin
  • Work with metals or toxins—lungs or skin


NETs may produce excess hormones. This can cause certain problems. In those that have them, symptoms will vary based on where the tumor is and what hormones are affected.

General symptoms of cancer may include:

  • Weight loss
  • Tiredness
  • Pain
  • Ongoing cough—with or without blood
  • Skin changes or sores that do not heal
  • Bleeding—especially from the GI tract
  • Digestive problems such as heartburn or problems swallowing
  • Problems passing urine (pee) or stool (poop)


The doctor will ask about symptoms and health history. A physical exam will be done. In some cases, a tumor is found while looking for something else.

Tests may include:

  • Blood and urine tests to look for hormone problems
  • Biopsy —some tissue is removed and checked under a microscope
  • Imaging tests such as:

The physical exam and test results help find the cancer stage. Staging helps guide a treatment plan. NETs are staged from 0 to 4. Stage 1 is a very localized cancer. Stage 4 is a spread to other parts of the body.


The treatment depends on the stage and type of cancer. In most cases, treatments are combined. Some can be used to ease symptoms caused by tumors or hormones that are causing problems.


There is no way to prevent NETs since the cause is unknown.


Surgery removes as much of the tumor as possible. If cancer has spread, nearby tissue or lymph nodes are also removed. Surgery may be done with a scope or as an open procedure.

Ablation is the use of heat, electricity, ethanol, or radiofrequency waves. This destroys the cancer using a small needle. Sometimes a probe is inserted into the tumor.





  • Neuroendocrine neoplasms (carcinoid tumors). EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/neuroendocrine-neoplasms-carcinoid-tumors.
  • Neuroendocrine tumor. Cancer.net website. Available at: http://www.cancer.net/cancer-types/neuroendocrine-tumors.
  • Oronsky B, Ma PC, et al. Nothing but NET: a review of neuroendocrine tumors and carcinomas. Neoplasia. 2017;19(12):991-1002.
  • Signs and symptoms of cancer. American Cancer Society website. Available at: https://www.cancer.org/treatment/understanding-your-diagnosis/signs-and-symptoms-of-cancer.html.


  • Mohei Abouzied, MD, FACP
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.