Overview

Carcinoid syndrome occurs when a rare cancerous tumor called a carcinoid tumor secretes certain chemicals into your bloodstream, causing a variety of signs and symptoms. Carcinoid tumors occur most commonly in the gastrointestinal tract or lungs.

Carcinoid syndrome typically occurs in people who have carcinoid tumors that are advanced. Treatment for carcinoid syndrome usually involves treating the cancer. However, because most carcinoid tumors don't cause carcinoid syndrome until they're advanced, a cure may not be possible. In those cases, medications may relieve your carcinoid syndrome symptoms and make you more comfortable.

Symptoms

The signs and symptoms of carcinoid syndrome depend on which chemicals the carcinoid tumor secretes into your bloodstream. The most common signs and symptoms of carcinoid syndrome include:

  • Skin flushing. The skin on your face and upper chest feels hot and changes color — ranging from pink to purple. Flushing episodes may last from a few minutes to a few hours or longer.

    Flushing may happen for no obvious reason, though sometimes it can be triggered by stress, exercise or drinking alcohol.

  • Facial skin lesions. Purplish areas of spiderlike veins may appear on the nose and upper lip.
  • Diarrhea. Frequent, watery stools sometimes accompanied by abdominal cramps may occur in people who have carcinoid syndrome.
  • Difficulty breathing. Asthma-like signs and symptoms, such as wheezing and shortness of breath, may occur at the same time you experience skin flushing.
  • Rapid heartbeat. Periods of a fast heart rate could be a sign of carcinoid syndrome.

When to see a doctor

Make an appointment with your doctor if you have signs and symptoms that concern you.

Causes

Carcinoid syndrome is caused by a carcinoid tumor that secretes serotonin or other chemicals into your bloodstream. Carcinoid tumors occur most commonly in your gastrointestinal tract, including your stomach, small intestine, appendix, colon and rectum, or in your lungs.

Only a small percentage of carcinoid tumors secrete the chemicals that cause carcinoid syndrome. In most cases, the liver effectively neutralizes the chemicals before they have a chance to travel through your body and cause symptoms.

However, when an advanced tumor spreads (metastasizes) to the liver itself, these tumors may secrete chemicals that aren't neutralized before reaching the bloodstream. Most people who experience carcinoid syndrome have an advanced cancer that has spread to the liver.

Some carcinoid tumors don't have to be advanced to cause carcinoid syndrome. For instance, carcinoid lung tumors that secrete chemicals into the blood do so farther upstream from the liver — not directly into the liver, where the chemicals are processed and eliminated.

Carcinoid tumors in the intestine, on the other hand, secrete their chemicals into blood that must first pass through the liver before reaching the rest of the body. The liver usually neutralizes the chemicals before they can affect the rest of the body.

What causes carcinoid tumors is unclear.

Complications

Having carcinoid syndrome can cause the following complications:

  • Carcinoid heart disease. Some people with carcinoid syndrome develop carcinoid heart disease. Carcinoid syndrome causes a thickening of the heart valves, making it difficult for them to function properly. As a result, the heart valves may leak.

    Signs and symptoms of carcinoid heart disease include fatigue and shortness of breath during physical activity. Carcinoid heart disease can eventually lead to heart failure.

    Your doctor may recommend medications for your heart. Surgical repair of damaged heart valves may be an option in advanced carcinoid heart disease.

  • Bowel obstruction. Cancer that spreads to the lymph nodes next to your small intestine can cause narrowing and kinking of your intestine, leading to a bowel obstruction.

    Signs and symptoms of a bowel obstruction include severe, cramping abdominal pain and vomiting. Surgery may be necessary to relieve the obstruction.

  • Carcinoid crisis. Carcinoid crisis causes a severe episode of flushing, low blood pressure, confusion and breathing difficulty.

    Carcinoid crisis can occur in people with carcinoid tumors when they are exposed to certain triggers, including anesthesia used during surgery. Carcinoid crisis can be fatal. Your doctor may give you medications before surgery to reduce the risk of carcinoid crisis.

July 01, 2015
References
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