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Neuroendocrine Tumors


Neuroendocrine tumors are a rare type of tumor that can make hormones. Hormones are usually made and released by the neuroendocrine system, which is made up of special tissues and glands. The endocrine tissue is partially controlled by the brain. Hormones affect specific body functions, such as metabolic rate, blood flow, breathing, or intestinal movements. They also alter levels of substances in the blood, such as glucose or calcium.

Neuroendocrine tumors require treatment of the tumor and management of issues created by hormonal changes. They can occur in areas throughout the body, such as:

  • Carcinoid tumors of the gastrointestinal (GI) tract, lungs, or thymus gland
  • Islet cell tumors of the pancreas
  • Merkel cell tumors of the skin
  • Adrenal gland tumors
  • Neuroblastoma—found in the cells that form the sympathetic nervous system (mostly in infants and children)
  • Ovaries, cervix, or uterus, though these tumors are rare

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

Islet Cells in the Pancreas

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Causes    TOP

Cancer occurs when cells in the body divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. Tumors that invade nearby tissues are called malignant and can spread to other parts of the body.

It is not clear exactly what causes the cells to lose growth control. Both genetics and environmental factors are believed to play a role.

Risk Factors    TOP

Risk factors depend on the type of cancer and where it develops. Examples of risk factors include:

  • A diet high in saturated fat (GI tract)
  • Smoking (lungs)
  • Excess sun exposure (skin)
  • Occupational exposure to metals or toxins (lungs, skin)

Symptoms    TOP

Neuroendocrine tumors may produce excess hormones, which can cause specific symptoms. 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:

  • Unexplained weight loss
  • Fatigue
  • Pain
  • Chronic cough with or without blood
  • Skin changes or sores that do not heal
  • Unexplained bleeding, especially from the GI tract
  • Digestive problems, such as heartburn or difficulty swallowing
  • Bladder and/or bowel changes

Diagnosis    TOP

Your doctor will ask you about your symptoms and medical history. A physical exam will be done. In some cases, a neuroendocrine tumor is found by accident when looking for something else.

Tests may include:

  • Blood and urine tests to look for hormone abnormalities
  • Biopsy—tissue removed and examined under a microscope
  • Imaging tests to locate tumors, which may include:

The doctor will use the results of these tests to determine the stage of cancer you have. Staging is used to guide your treatment plan. Like other cancers, neuroendocrine tumors are staged from I-IV. Stage I is a very localized cancer, while stage IV indicates a spread to other parts of the body.

Treatment    TOP

Cancer treatment varies depending on the stage and type of cancer. A combination of therapies is most effective. For example, radiation may be used before surgery to shrink the tumor or after to make sure all the cancer has been removed. Treatments may also be needed to help manage symptoms caused by hormone secretions.


Surgery is done to remove as much of the tumor as possible. Nearby tissue or lymph nodes may also be removed if there are signs that the cancer has spread.

Ablation is the use of heat, electricity, ethanol, or radiofrequency waves to destroy cancerous tissue using a small needle or probe is inserted into the tumor. Though it is beneficial to avoid open surgery, it is only appropriate for smaller tumors.

Radiation Therapy

Radiation therapy is the use of radiation to kill cancer cells and shrink remaining tumors. Current radiation therapy is designed to focus on tumor but healthy cells can be affected as well. This can cause a range of side effects.

Chemotherapy    TOP

Chemotherapy is the use of drugs to kill cancer cells. It may be given in many forms including pill, injection, or IV. The drugs enter the bloodstream. Chemotherapy travels through the body killing mostly cancer cells. Some healthy cells are killed as well, which can cause a range of side effects.

Medications    TOP

Medications have various roles. They may be used to:

  • Control or block the effects of hormones released by the tumor
  • Fight or manage cancer in other ways such as increasing the body’s own immune system or blocking growth of blood vessels needed to supply the tumor
  • Treat side effects cancer treatment

Prevention    TOP

There are no current guidelines to prevent neuroendocrine tumors.


American Cancer Society
National Cancer Institute


Canadian Cancer Society
Public Health Agency of Canada


Carcinoid tumors. EBSCO DynaMed Plus website. Available at: Updated May 24, 2016. Accessed September 6, 2016.
Kulke MH, Benson AB 3rd, Bergsland E, et al. Neuroendocrine tumors. J Natl Compr Cancer Netw. 2012;10(6):724-764.
Neuroendocrine tumor. website. Available at:
...(Click grey area to select URL)
Updated April 2014. Accessed September 6, 2016.
Signs and symptoms of cancer. American Cancer Society website. Available at:
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Updated August 11, 2014. Accessed September 6, 2016.
Warner RR. Enteroendocrine tumors other than carcinoid: A review of clinically significant advances. Gastroenterology. 2005;128(6):1668-1684.
Last reviewed May 2016 by Mohei Abouzied, MD

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