Causes

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.

Exams 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.

Support Groups

Learn more about carcinoid syndrome and get support from:

• The Carcinoid Cancer Foundation
• The Caring for Carcinoid Foundation

Outlook (Prognosis)

The outlook in patients with carcinoid syndrome is different from the outlook in patients who have carcinoid tumors without the syndrome.

In people with the syndrome, the tumor has usually spread to the liver, which lowers the survival rate. People with carcinoid syndrome are also more likely to have a separate cancer (second primary tumor) at the same time.

The outlook is more favorable thanks to new treatment methods, such as Sandostatin.

Possible Complications

• Increased risk of falls and injury (from low blood pressure)
• Bowel obstruction (from tumor)
• Gastrointestinal bleeding
• Heart valve failure

When to Contact a Medical Professional

Call for an appointment with your health care provider if you have symptoms of carcinoid syndrome.

Prevention

Treating the tumor reduces the risk of carcinoid syndrome.

References

Hande KR. Multiple-organ syndromes: Carcinoid syndrome. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 251.

Kulke MH. Clinical presentation and management of carcinoid tumors. Hematol Oncol Clin North Am. 2007;21:433-455.

National Cancer Institute. Gastrointestinal carcinoid treatment PDQ. Updated May 16, 2008.

National Comprehensive Cancer Network. Clinical practice guidelines in oncology. Neuroendocrine tumors. v.2.2010.

Updated: 4/26/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.