Slideshows Images Quizzes
font size

Carcinoid Syndrome (Carcinoid Tumor)

Medical Author:
Medical Editor:
Medical Editor:

Carcinoid tumor definition and facts

  • Carcinoid tumors are rare tumors that develop from hormone-producing cells called enterochromaffin cells that occur throughout the body, with approximately 65% originating in the gastrointestinal tract and 25% in the lungs.
  • Carcinoid tumors can occur almost anywhere in the gastrointestinal tract but primarily in the stomach, small intestine, appendix, colon, and rectum.
  • Carcinoid tumors can be benign (non-cancerous) or malignant (cancerous). Even when they are malignant, carcinoid tumors usually are slow to grow and to spread.
  • The carcinoid syndrome is a syndrome that is caused by the release of hormones and other chemical substances called vasoactive amines from the carcinoid tumor.
  • The carcinoid syndrome may include signs and symptoms such as
  • Carcinoid tumors can be found by endoscopy, barium small intestinal X-ray studies, and by capsule enteroscopy. Their diagnosis requires a biopsy to provide a tissue sample.
  • Metastatic carcinoid tumors can be diagnosed by CT or MRI scans, indium 111 octreotide scans, and bone scans.
  • Carcinoid tumors can be managed and treated with observation, surgery, cryotherapy, radiofrequency ablation, hepatic artery embolization, interferon therapy, chemotherapy, and radiation therapy.
  • The carcinoid syndrome's signs or symptoms can be blocked or lessened by medication.
  • The prognosis and survival rate for someone with carcinoid tumor varies with the extent of the metastatic disease in the presence of the carcinoid syndrome. The clinical course of these cancers is often indolent with 5 year survival approaching 75%. Current treatment is not curative, but patients can be helped by palliative measures.

What is a carcinoid tumor?

A carcinoid tumor is a tumor that develops from enterochromaffin cells. Enterochromaffin cells are hormone- and chemical-producing cells that normally are found in the small intestine, appendix, colon, rectum, bronchi, pancreas, ovaries, testes, bile ducts, liver, as well as other organs. Enterochromaffin cells produce many types of substances for example, histamine, serotonin, dopamine, tachykinins, and other chemicals that have profound effects on the circulatory system (heart and blood vessels), the gastrointestinal tract, and the lungs. These substances are therefore called vasoactive amines. For example, serotonin can cause diarrhea, histamine wheezing, and tachykinins flushing due to dilation of blood vessels.

Since carcinoid tumors develop from enterochromaffin cells, they frequently retain the capability of producing the same hormones, often in large quantities. When these hormones circulate in the blood, they can cause symptoms of carcinoid syndrome, which is discussed later.

The important characteristic of carcinoid tumors that sets them apart from other gastrointestinal tract tumors is their potential to cause the carcinoid syndrome. Most other gastrointestinal tract tumors (such as colon cancers or small bowel lymphomas) cause symptoms primarily due to their local effects on the intestines such as abdominal pain, intestinal bleeding, and intestinal obstruction. Although carcinoid tumors may also cause these local symptoms, they may also produce and release the substances that cause the carcinoid syndrome. Often, symptoms of the carcinoid syndrome can be more devastating than the local symptoms.

What is carcinoid syndrome?

The carcinoid syndrome is a combination of symptoms caused by the hormones and other chemical substances released by the tumors into the blood stream. The symptoms of the carcinoid syndrome vary depending on which hormones are released by the tumors. The common hormones released are serotonin, bradykinin (a molecule produced by enzymes at the site of an injury and then binds to receptors to cause pain), histamine, and chromogranin A (a general marker for neuroendocrine tumors).

Medically Reviewed by a Doctor on 8/22/2016


GI Disorders

Get the latest treatment options.

Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations

Health Solutions From Our Sponsors