Carcinoid Syndrome

Written by Ann Pietrangelo | Published on September 16, 2012
Medically Reviewed by George Krucik, MD

What Is Carcinoid Syndrome?

Carcinoid syndrome is a condition in which a carcinoid tumor secretes chemicals into your bloodstream. These tumors are rare and cancerous. They are usually located in your gastrointestinal tract or lungs.

According to the National Library of Medicine, carcinoid syndrome only develops in one out of 10 cases of carcinoid tumors. (NLM) It occurs most often in patients whose cancer has spread (metastasized) to their liver or lungs.

Treatment for carcinoid syndrome involves treating the cancer, which may include chemotherapy or surgery to remove any tumors. If the tumors can be completely removed, your long-term outlook is very good.

However, since most cases of carcinoid syndrome develop in the advanced stages of cancer, full recovery may not be possible. However, your doctor can prescribe medications to relieve some of the specific symptoms of your condition.

Causes of Carcinoid Syndrome

Carcinoid syndrome occurs when you have a carcinoid tumor that is secreting chemicals—such as serotonin—into your bloodstream. The chemicals cause your blood vessels to dilate, or open up. Most carcinoid tumors do not secrete chemicals that cause this condition. If a carcinoid tumor does secrete chemicals, the liver often neutralizes them before they can spread through your body.

Typically, carcinoid syndrome is a sign that your cancer has spread to your liver or lungs. According to the National Cancer Institute, 58 to 64 percent of people with carcinoid tumors of the small intestine already have metastatic disease in the lymph nodes or liver. (NCI)

The cause of these tumors is unknown. However, carcinoid tumors are most likely to form in your gastrointestinal tract—which includes your appendix, stomach, small intestine, colon, and rectum—or in your lungs.

Symptoms of Carcinoid Syndrome

On their own, carcinoid tumors often produce no symptoms. The symptoms of carcinoid syndrome vary, depending on the particular chemicals that are secreted into your blood. Symptoms may include:

  • flushing (your face and chest will feel hot and the skin will appear red, pink, or purple, lasting from a few minutes to several hours)
  • skin lesions or purple spider veins on the upper lip and nose
  • diarrhea
  • shortness of breath or wheezing
  • rapid heartbeat or heart palpitations
  • low blood pressure

Symptoms can be triggered or made worse by certain activities, such as stress or heavy exercise. Consuming alcohol or rich foods, such as chocolate, red wine, or blue cheese, can also worsen flushing and other symptoms of carcinoid syndrome.

If you have symptoms of carcinoid syndrome, see your doctor.

How Carcinoid Syndrome Is Diagnosed

Usually, your doctor will discover this condition while performing other tests, such as a pre-surgery blood test.

He or she will make a diagnosis based on your symptoms, a physical examination, and additional tests, such as:

  • blood tests to check the levels of certain chemicals—such as the protein chromogranin A—which can come from carcinoid tumors
  • urine tests to see how your body is processing serotonin
  • imaging tests, such as an MRI or CT scan

Treating Carcinoid Syndrome

Treating carcinoid tumors will decrease your chances of developing carcinoid syndrome. If you do develop the syndrome, your doctor will first try to treat the cancer and then address your specific symptoms.

Depending on your situation, your doctor may choose to surgically remove the tumors or to shrink them using chemotherapy. He or she may also prescribe medications that prevent the tumors from releasing harmful chemicals or that slow their growth.

Other treatment options include:

  • hepatic artery embolization: a procedure in which tumors are cut off from their blood supply
  • radiofrequency ablation: a procedure in which cancer cells are killed using heat
  • cryotherapy: a treatment that freezes cancer cells

Long-Term Outlook for Carcinoid Syndrome

Your long-term outlook depends on the specifics of your condition and treatment. Carcinoid syndrome can be cured if the tumor is completely removed through surgery.

This condition can lead to several life-threatening complications. Carcinoid heart disease may cause your heart valves to thicken and leak. This can lead to fatigue, shortness of breath during physical activity, and possible heart failure.

Carcinoid crisis is another potentially fatal complication marked by extremely low blood pressure, flushing, breathing difficulties, and confusion. It can be triggered by anesthesia before surgery.

If your tumors are located in the lymph nodes near your small intestines, you are at a higher risk for developing a bowel obstruction. Symptoms of a bowel obstruction include cramping, abdominal pain, and vomiting. Carcinoid syndrome can also cause bleeding in your gastrointestinal tract.

The low blood pressure caused by carcinoid syndrome may also increase your risk of falling down and injuring yourself.

If you have carcinoid syndrome, you can take certain steps to reduce your symptoms. Try to avoid:

  • triggers that cause flushing and other symptoms—particularly foods high in tyramine, such as aged cheeses, avocado, and processed foods
  • large meals
  • alcohol

Selective serotonin reuptake inhibitors—such as fluoxetine (Prozac) and paroxetine (Paxil)—can make your symptoms worse. If you take these medications, ask your doctor if there are safer alternatives. Never stop taking medications without consulting with your doctor first.

If you suffer from diarrhea, ask your doctor if you should take a multivitamin supplement to replace lost nutrients.

It can be helpful to talk to other people who are coping with the same condition. Ask your doctor or hospital for information about support groups in your area.

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