Carcinoid cancer and related neuroendocrine tumors (NETs) are small, slow growing tumors found mostly in the gastrointestinal system, but can be in other parts of the body such as the pancreas and the lung. Since most of these grow very slowly, compared to other cancers, it usually takes many years before they become sizable or cause symptoms.
Carcinoid tumors and other NETs usually originate in hormone-producing cells that line the small intestine or other cells of the digestive tract. They can also occur in the pancreas, testes, ovaries, or lungs. Carcinoid tumors can produce an excess of hormonelike substances, such as serotonin, bradykinin, histamine, and prostaglandins. Excess levels of these substances can sometimes result in a diverse set of symptoms called carcinoid syndrome. Other NETs can produce other hormonal substances causing a variety of other syndromes.
When carcinoid tumors occur in the digestive tract or pancreas, the substances they produce are released into a blood vessel that flows directly to the liver (portal vein), where enzymes destroy them. Therefore, carcinoid tumors that originate in the digestive tract generally do not produce symptoms unless the tumors have spread to the liver. The hormones secreted by other NETs, particularly those in the pancreas, do not necessarily require spread to the liver to cause symptoms.
When carcinoid tumors have spread to the liver, the liver is unable to process the substances before they begin circulating throughout the body. Depending on which substances are being released by the tumors, the person will have the various symptoms of carcinoid syndrome, insulinoma syndrome, Zollinger Ellison syndrome, VIPoma syndrome, etc. Carcinoid tumors of the lungs, testes, and ovaries also cause symptoms without having spread, because the substances they produce bypass the liver and can sometimes circulate widely in the bloodstream.
Source: The Carcinoid Cancer Foundation, a RITA Foundation supporter. Visit their website for more information on Carcinoid Cancer.
Carcinoid Syndrome
Carcinoid syndrome is a group of symptoms associated with carcinoid tumors -- tumors of the small intestine, colon, appendix, and bronchial tubes in the lungs.
Causes, Incidence, and Risk Factors
Carcinoid syndrome is the pattern of symptoms sometimes seen in people with carcinoid tumors. These tumors are rare, and often slow growing. About 70% of carcinoid tumors are found in the gastrointestinal tract.
Carcinoid syndrome occurs in about 1 in 10 people with carcinoid tumors, usually after the tumor has spread to the liver or lung.
These tumors release too much of the hormone serotonin, as well as several other chemicals that cause the blood vessels to open (dilate).
Symptoms
Most carcinoid tumors have no symptoms. When symptoms do occur, they may include:
- Abdominal pain that comes and goes
- Bright red flushing of the face, neck, or upper chest
- Diarrhea
- Heart palpitations
- Low blood pressure
- Wheezing
Sometimes symptoms are brought on by physical exertion, or eating or drinking things such as blue cheeses, chocolate, or red wine.
Signs and Tests
Most of these tumors are found when tests or procedures are done for other reasons, such as during abdominal surgery. A physical examination may show:
- Heart valve lesions
- Signs of niacin-deficiency disease (pellagra)
Tests may include:
- 5-HIAA levels in urine
- Blood tests (including serotonin blood test)
- CT and MRI scan of the chest or abdomen
- Octreotide radiolabelled scan
Treatment
Surgery to remove the tumor is usually the first treatment. It can permanently cure the condition if the tumor is completely removed. If the tumor has spread to the liver, treatment involves destroying the local blood supply of the tumor or giving chemotherapy directly into the liver.
When the entire tumor cannot be removed, removing large portions of the tumor ("debulking") can help relieve the symptoms.
Octreotide injections are sometimes given to people with advanced carcinoid tumors that cannot be removed with surgery. Interferon is often given with octreotide to help stop tumor growth. Patients whose carcinoid tumor secretes histamine will benefit from treatment with antihistamine drugs.
People with carcinoid syndrome should avoid alcohol, large meals, and foods high in tyramine (aged cheeses, avocado, many processed foods), because they may trigger symptoms.
Some common medicines, like selective serotonin reuptake inhibitors (SSRIs), such as paroxetine (Paxil) and fluoxetine (Prozac), may make symptoms worse by increasing levels of serotonin. However, do not stop taking these medicines unless your doctor tells you to do so.
Source: National Center for Biotechnology Information. Visit their website for more information on Carcinoid Cancer.