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by EBSCO Medical Review Board

Definition

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 occurs, it is called neuroendocrine carcinoma.

Islet Cells in the Pancreas
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Causes

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

Risk Factors

The chances of NETs depend on the type of cancer. Your chances are higher if you:

  • 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

Symptoms

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

General symptoms of cancer may include:

  • Weight loss
  • Fatigue
  • Pain
  • Chronic 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
  • Bladder or bowel changes

Diagnosis

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

You may have:

  • Blood and urine tests to look for hormone problems
  • Biopsy —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 0-4. Stage 1 is a very localized cancer. Stage 4 is a spread to other parts of the body.

Treatment

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.

Procedures

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.

Radiation Therapy

Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. radiation may be used before surgery to shrink the tumor or after to make sure all the cancer has been removed.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. It may given by mouth, shots, or IV. The drugs enter the bloodstream and travel throughout the body. It also may be used before or after surgery.

Medicines

Medicines are used to:

  • Control or block hormones released by the tumor.
  • Boost or change the body’s immune system by blocking growth of blood vessels that make the tumor grow.
  • Ease problems related to cancer treatment.

Prevention

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

RESOURCES

American Cancer Society  https://www.cancer.org 

National Cancer Institute  https://www.cancer.gov 

CANADIAN RESOURCES

Canadian Cancer Society  https://www.cancer.ca 

Health Canada  https://www.canada.ca 

References

Kulke MH, Benson AB 3rd, Bergsland E, et al. Neuroendocrine tumors. J Natl Compr Cancer Netw. 2012;10(6):724-764.

Neuroendocrine tumor. Cancer.net website. Available at: http://www.cancer.net/cancer-types/neuroendocrine-tumor. Accessed January 29, 2021.

Neuroendocrine tumors. EBSCO DynaMed website. Available at: https://www.dynamed.com/topics/dmp~AN~T576496/Neuroendocrine-tumors. Accessed January 29, 2021.

Signs and symptoms of cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/cancer-basics/signs-and-symptoms-of-cancer.html. Accessed January 29, 2021.

Warner RR. Enteroendocrine tumors other than carcinoid: A review of clinically significant advances. Gastroenterology. 2005;128(6):1668-1684.

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