Carcinoid syndrome is a condition in which a carcinoid tumor releases serotonin or other chemicals into the bloodstream.

Carcinoid tumors, which develop most commonly in the gastrointestinal (GI) tract or lungs, are rare.

These tumors cause carcinoid syndrome only about 10 percent of the time. This usually happens after cancer has spread. Tumors in the liver are the most likely cause of symptoms.

The average age of those with GI carcinoid tumor diagnosis is early 60s. Carcinoid syndrome is slightly more common in women than in men and more common in African Americans than in white people.

Signs and symptoms of carcinoid syndrome depend on the chemicals the tumor emits into the bloodstream. Some of the most common symptoms are:

  • Flushing of the skin lasting from a few minutes to several hours. The skin on the face, head, and upper chest feels hot and color turns pink or purple. Flushing can be prompted by factors such as exercise, drinking alcohol, or stress, but can happen without apparent cause.
  • Purple spider veins. These typically appear on your nose and upper lip.
  • Diarrhea and abdominal cramps.
  • Shortness of breath or wheezing. This sometimes happens along with flushing.

Other symptoms can include:

  • muscle and joint aches
  • rapid heart rate
  • stomach pain
  • feeling faint or weak

Carcinoid syndrome happens when a carcinoid tumor produces too many hormone-like substances. These may include serotonin, bradykinins, tachykinins, and prostaglandins.

When tumors are in the GI tract, the body is usually able to neutralize these substances.

When tumors are outside the GI tract, such as the liver or ovaries, the substances can’t be broken down. In these cases, the substances are released into the bloodstream which causes carcinoid syndrome symptoms.

Carcinoid tumors can develop anywhere in the body that has neuroendocrine cells. The cause isn’t clear, but risk factors may include:

Carcinoid tumors grow slowly and don’t always cause symptoms. You may not know you have them until they’ve metastasized, or spread, to the liver and caused carcinoid syndrome.

Treatment for carcinoid syndrome involves treating the cancer. If possible, a doctor will surgically remove some or all of the tumors.

Hepatic artery embolization

This procedure can be used to cut off the blood supply to carcinoid tumors in the liver. During this procedure, the surgeon inserts a catheter near the groin to reach the main artery to the liver.

Then, embolic inert particles are used to clog the artery and block the tumor’s blood supply. Sometimes, chemotherapy drugs such as cisplatin, doxorubicin, or mitomycin are injected as well. Other blood vessels will continue to nourish healthy liver cells.

Radiofrequency ablation or cryotherapy

Other methods used to destroy cancer cells are radiofrequency ablation and cryotherapy. Radiofrequency ablation uses heat and cryotherapy uses cold. They’re both delivered directly to the tumor through a needle.


Medications to help slow tumor growth or stop them from secreting chemicals include:

  • octreotide (Sandostatin)
  • lanreotide (Somatuline Depot)
  • telotristat (Xermelo)
  • interferon alfa

Systemic chemotherapy drugs used to treat carcinoid tumors include:

  • 5-fluorouracil
  • cisplatin
  • cyclophosphamide
  • dacarbazine
  • doxorubicin
  • streptozotocin
  • VP-16 (etoposide)

Certain foods can contribute to symptoms like flushing, diarrhea, gas, bloating, and abdominal pain. Changing your diet won’t cure carcinoid syndrome, but it may help you feel better.

Everyone is different. It’s worth keeping a food diary to track symptoms and note how your body reacts to certain foods. Some common triggers are:

  • high-fat meals
  • raw tomatoes
  • spicy foods
  • foods with a lot of amines

Foods very high in amines

Foods very high in amines include:

  • aged cheese
  • sauerkraut and some other fermented foods
  • spinach
  • canned tuna
  • dark chocolate
  • sodas
  • smoked, salted, or pickled meats and fish
  • yeast extracts and hydrolyzed proteins

Foods with high amines

Foods with a high number of amines are:

  • avocado, banana, raspberries, fig, pineapple
  • eggplant, mushroom, tomato
  • aged meats, frozen fish
  • peanuts
  • coconut
  • soy sauce and vinegar
  • beer, wine
  • cocoa

Foods low in amines

Foods lower in amines are:

  • lean meat, poultry, fish
  • grains, starchy foods with low fiber
  • low-fat dairy
  • most vegetables
  • soy milk, edamame
  • unaged cheeses
  • almonds and cashews
  • eggs

Additional diet tips

Here are some other tips that may help improve symptoms:

  • Try eating four to six smaller meals a day rather than three big meals.
  • Choose cooked over raw vegetables for easier digestion.
  • If you’re prone to diarrhea, avoid wheat bran, prunes, dried fruit, and popcorn.
  • Maintain a higher protein diet. Include poultry, lean meats, beans and lentils, eggs, and low-fat dairy.
  • Lower your fat intake. Healthy fats include extra virgin olive oil, nuts, and seeds.

Chronic diarrhea can result in nutritional deficiencies. Talk to your doctor about multivitamins or other dietary supplements that may help.

Your doctor can refer you to a nutritionist or registered dietician to help address all your nutritional needs.

Tests used to help your doctor with a diagnosis may include:

  • 5-HIAA urine test to check for certain substances in the urine
  • blood tests to measure serotonin and other substances in the blood
  • imaging tests, such as CT scan, MRI, and other imaging tests to help locate tumors
  • biopsy to determine if a tumor is cancerous

As carcinoid syndrome progresses, it can lead to:

In extremely rare cases, acute symptoms such as low blood pressure, palpitations, faintness, and shortness of breath may become life-threatening. This is called carcinoid crisis. In some people, these symptoms are triggered by stress, intense exercise, or alcohol.

Carcinoid syndrome can have a significant impact on your quality of life. It can affect how you eat, exercise, and function on a day-to-day basis.

Carcinoid syndrome usually occurs with advanced carcinoid cancer, or cancer that’s metastasized to a distant site.

Cancer survival rates are based on the stage at diagnosis. The 5-year relative survival rates for GI carcinoid cancer are:

  • localized: 98 percent
  • regional: 93 percent
  • distant: 67 percent

These figures are based on people diagnosed between 2008 and 2014. Keep in mind that cancer treatments change quickly. There’s a chance the general prognosis has improved since these figures were compiled.

In addition, these are only general survival rates. Your prognosis depends on a variety of factors, including your age and overall health. Your oncologist can review your medical history, assess your response to treatment, and provide a more personalized outlook.

The hallmark signs and symptoms of carcinoid syndrome are:

If you have these symptoms, it doesn’t mean you have carcinoid syndrome. They could be due to something else entirely. However, it’s important to see your doctor for an accurate diagnosis and treatment.

Carcinoid syndrome is a group of symptoms caused by carcinoid tumors. You should see your doctor if you notice any of the symptoms mentioned above.

If you receive a carcinoid syndrome diagnosis, you’ll need to work closely with a team of doctors, which may include an oncologist, a surgeon, a gastroenterologist, and a radiation oncologist.

Palliative care specialists and dietitians can also help you manage symptoms.