Carcinoid syndrome

Definition

Carcinoid syndrome is a group of symptoms associated with carcinoid tumor (see bronchial adenoma).

Causes

Carcinoid syndrome is the pattern of symptoms seen in people with carcinoid tumors. These tumors may occur in the small intestine, colon, bronchial tubes, or appendix.

Carcinoid tumors secrete excessive amounts of the hormone serotonin as well as other chemicals that cause the blood vessels to dilate (open). These tumors may also cause diarrhea and wheezing (asthma).

There are wide variations in the chemicals secreted by these tumors, and the symptoms depend on the mix of chemicals made by the particular tumor.

Normally, an amino acid called tryptophan is used by the body to make niacin and certain proteins, but in carcinoid syndrome, it forms serotonin instead. Most serotonin is changed by the body to 5-hydroxy indole acetic acid (5-HIAA).

The most bothersome symptoms include bright red facial flushing, diarrhea (which may be explosive and severe) and occasionally wheezing. A specific type of heart valve damage may occur, as well as other cardiac problems.

In children, carcinoid tumors usually occur in the appendix, and removal of the appendix usually results in a complete cure.

Symptoms

• Abdominal pain, intermittent
• Flushing
• Diarrhea
• Wheezing
• Heart palpitations
• Low blood pressure

Exams and Tests

5-HIAA levels in urine are higher than normal in 75% of cases. Certain foods and medicines must be avoided for a couple of days before this test, and on the day the urine is collected. These include bananas, pineapple and its juice, red plums, avocado, walnuts, kiwi fruit, tomatoes, various cough medicines, muscle-relaxing medicines, acetaminophen (Tylenol), caffeine, fluorouracil, iodine solutions, phenacetin, MAO inhibitors (certain anti-depressant drugs), isoniazid, and phenothiazine drugs (Compazine, Thorazine).

Blood tests may show higher than normal levels of serotonin levels and chromogranin A, and lower than normal levels of tryptophan.

The OctreoScan is a scanning test used to identify most carcinoids and other neuroendocrine tumors. A CT and MRI scan may be done along with the OctreoScan to see how well treatment of the carcinoid tumor is working.

Less frequent blood tests may check levels of histamine, bradykinin, neurone-specific enolase, calcitonin, Substance-P, neurokinin-A, and pancreatic polypeptide.

An examination may show heart valve lesions or signs of niacin-deficiency disease (pellagra).

Treatment

Surgery to completely remove the tumor is usually the first line of treatment. It can result in permanent cure if the tumor is entirely removed.

When the entire tumor cannot be removed, removing large portions of the tumor (debulking) can help relieve the symptoms.

Sandostatin (octreotide) injections are given to those with advanced carcinoid tumors that cannot be removed surgically. In many cases, this drug blocks and reverses the growth of the tumors.

Interferon is another drug often given with octreotide. It helps stop the growth of the tumor.

A serotonin antagonist may be prescribed to control diarrhea and inadequate absorption of nutrients from the intestines (malabsorption).

Some common medicines, like selective serotonin reuptake inhibitors (SSRIs, such as Paxil, Serzone, and Prozac) may make symptoms worse by increasing levels of serotonin. However, these medicines should be stop ONLY if your doctor tells you to do so.

One of several combinations of chemotherapy may be given by IV or by mouth. If one combination is does not work, another combination may be effective. About one-third of patients benefit from chemotherapy.

Increased protein and a low-fat diet are often recommended. Multivitamin mineral and low-dose nicotinic acid (niacin) supplements may be prescribed. Other items sometimes recommended are fish oil capsules, electrolyte supplements, and in some cases, large portions of nutmeg. Patients are advised to ingestion of alcohol, large meals, and foods high in tyramine, as these may provoke symptoms.

Support Groups

Learn more about carcinoid syndrome and get support from:

• The Carcinoid Cancer Foundation
• The Caring for Carcinoid Foundation

Outlook (Prognosis)

The course of the illness in patients with carcinoid syndrome is different than those patients who have carcinoid tumors without the syndrome. The outlook is more favorable with the addition of new treatment methods, such as Sandostatin and others. The survival rate is variable.

Possible Complications

• Hypotension increases the risk of falls and subsequent injury
• Gastrointestinal bleeding
• Bowel obstruction from tumor mass
• Right-sided heart failure

When to Contact a Medical Professional

Call for an appointment with your health care provider if symptoms occur that are suggestive of carcinoid syndrome.

Prevention

Treatment of the associated tumor reduces the risk of carcinoid syndrome.

Email to a Friend