Overview

Neuroendocrine tumors are cancers that begin in specialized cells called neuroendocrine cells. Neuroendocrine cells have traits similar to those of nerve cells and hormone-producing cells.

Neuroendocrine tumors are rare and can occur anywhere in the body. Most neuroendocrine tumors occur in the lungs, appendix, small intestine, rectum and pancreas.

There are many types of neuroendocrine tumors. Some grow slowly and some grow very quickly. Some neuroendocrine tumors produce excess hormones (functional neuroendocrine tumors). Others don't release hormones or don't release enough to cause symptoms (nonfunctional neuroendocrine tumors).

Diagnosis and treatment of neuroendocrine tumors depend on the type of tumor, its location, whether it produces excess hormones, how aggressive it is and whether it has spread to other parts of the body.

Types

Symptoms

Neuroendocrine tumors don't always cause signs and symptoms at first. The symptoms you might experience depend on the location of your tumor and whether it produces excess hormones.

In general, neuroendocrine tumor signs and symptoms might include:

  • Pain from a growing tumor
  • A growing lump you can feel under the skin
  • Feeling unusually tired
  • Losing weight without trying

Neuroendocrine tumors that produce excess hormones (functional tumors) might cause:

  • Skin flushing
  • Diarrhea
  • Frequent urination
  • Increased thirst
  • Dizziness
  • Shakiness
  • Skin rash

When to see a doctor

Make an appointment with your doctor if you have any persistent signs and symptoms that worry you.

Causes

The exact cause of neuroendocrine tumors isn't known. These cancers begin in neuroendocrine cells that have traits similar to those of nerve cells and hormone-producing cells. Neuroendocrine cells are found throughout your body.

Neuroendocrine tumors begin when neuroendocrine cells develop changes (mutations) in their DNA. The DNA inside a cell contains the instructions that tell the cell what to do. The changes tell the neuroendocrine cells to multiply rapidly and form a tumor.

Some neuroendocrine tumors grow very slowly. Others are aggressive cancers that invade and destroy normal body tissue or spread (metastasize) to other parts of the body.

Risk factors

The risk of neuroendocrine tumors is higher in people who inherit genetic syndromes that increase the risk of cancer. Examples include:

  • Multiple endocrine neoplasia, type 1 (MEN 1)
  • Multiple endocrine neoplasia, type 2 (MEN 2)
  • Von Hippel-Lindau disease
  • Tuberous sclerosis
  • Neurofibromatosis

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Neuroendocrine tumors care at Mayo Clinic

June 03, 2021
  1. Neuroendocrine and adrenal tumors. Plymouth Meeting, Pa.: National Comprehensive Cancer Network. https://www.nccn.org/professionals/physician_gls/default.aspx. Accessed June 4, 2019.
  2. Neuroendocrine tumors: Introduction. Cancer.net. https://www.cancer.net/cancer-types/neuroendocrine-tumors/introduction. Accessed June 6, 2019.
  3. Warner KJ. Allscripts EPSi. Mayo Clinic, Rochester, Minn. April 29, 2019.

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