What is a Carcinoid Tumor?

What is a Carcinoid Tumor?

A carcinoid tumor is a type of slow-growing cancer that starts in neuroendocrine cells. It’s a type of neuroendocrine tumor (NET).

Neuroendocrine cells are found throughout your body, especially your gastrointestinal (GI or digestive) system. They help your body produce hormones and control the release of digestive juices.

Like other types of cells, neuroendocrine cells can change and become cancerous, growing out of control. This forms a carcinoid tumor.

Carcinoid tumors can start in many parts of your body, most often in your ileum (lower section of your small intestine). But they also occur in your:

  • Appendix.
  • Kidneys.
  • Lungs.
  • Ovaries.
  • Pancreas.
  • Rectum.
  • Stomach.

Even though carcinoid tumors are slow-growing, they can spread to other organs.

What’s the difference between a carcinoid tumor and carcinoid syndrome?

The excess chemicals produced by carcinoid tumors can produce symptoms, which is called carcinoid syndrome. Only about 10% of people with carcinoid tumors develop carcinoid syndrome.

Who might get a neuroendocrine tumor?

People with certain medical conditions are more likely to develop a carcinoid tumor:

  • Atrophic gastritis, a chronic inflammatory disease in your GI tract.
  • Familial small bowel neuroendocrine tumor, which causes tumors in your small intestine.
  • Multiple endocrine neoplasia (MEN) type I, which causes tumors in the glands of your endocrine system.
  • Neurofibromatosis type 1 (NF1).
  • Tuberous sclerosis complex (TSC).
  • Von Hippel Lindau (VHL) disease.

How common are carcinoid tumors?

Carcinoid tumors affect about 4 of every 100,000 adults. They’re even rarer in children.

Are carcinoid tumors benign or malignant?

Carcinoid tumors are a type of cancer, which means they’re malignant.

Symptoms and Causes

What causes a carcinoid tumor?

Researchers don’t know what triggers the cell growth that causes carcinoid tumors. They have, however, linked them to inherited syndromes, including:

  • Multiple endocrine neoplasia type 1 (MEN1), which causes your thyroid, parathyroid or adrenal glands to be overactive or form tumors.
  • Multiple endocrine neoplasia type 2 (MEN2), which causes your pancreas, pituitary or parathyroid to be overactive or form tumors.
  • Von Hippel-Lindau syndrome, a rare condition where benign tumors grow in various parts of your body.
  • Neurofibromatosis type 1, a rare condition where tumors grow on your skin and nerves, affecting your eyes and other parts of your body.

What are carcinoid tumor symptoms?

The symptoms of a carcinoid tumor depend on:

  • Location of the tumor.
  • Severity of disease (how advanced it is).
  • What kinds of hormones the tumor releases.

Many carcinoid tumors don’t cause any symptoms, especially at first. But signs may appear when excess chemicals cause symptoms or when a tumor spreads (metastasizes).

One of the most common symptoms is flushing on your face and neck. Your skin may suddenly become red and hot. Flushing may be triggered by stress, alcohol and certain foods.

Other symptoms may include:

  • Abdominal pain.
  • Anemia (low red blood cells).
  • Diarrhea.
  • Fatigue or weakness.
  • Heart murmur due to heart muscle damage.
  • Jaundice (yellowing of your skin).
  • Low blood pressure (hypotension).
  • Nausea and vomiting.
  • Rectal bleeding.
  • Shortness of breath (dyspnea).
  • Unexplained weight loss.
  • Wheezing.

A carcinoid tumor also can lead to certain syndromes:

  • If a tumor makes too much cortisol (often called the stress hormone), you can develop Cushing syndrome.
  • If the tumor makes too much gastrin, your body produces too much stomach acid. That can lead to ulcers and Zollinger-Ellison syndrome.
  • With too much serotonin, you can develop carcinoid syndrome, leading to several symptoms listed above.

Diagnosis and Tests

How is NET diagnosed?

Carcinoid tumors often are found by accident when people are getting tests for other conditions. For example, a healthcare provider may find a carcinoid tumor during:

  • Colonoscopy (lower endoscopy) to screen for colon cancer.
  • Surgery to remove an appendix when a person has appendicitis.
  • Upper endoscopy to look for an ulcer.

But if a healthcare provider suspects you have a carcinoid tumor based on flushing or other symptoms, they may order:

  • Biochemical tests, which measure the amounts of certain hormones and chemicals in a blood or urine sample.
  • Endoscopy, which uses a thin tube with a light and camera on the end to look inside of your GI tract.
  • Other imaging tests to take pictures inside of your body, such as CT scan, PET scan or MRI.

How are carcinoid tumors classified?

Based on the test results, your healthcare provider may classify or grade the carcinoid tumor. One way to classify a tumor is by location:

  • Localized: The tumor is in one location and hasn’t spread.
  • Metastatic: A malignant carcinoid tumor has spread to other parts of your body, far away from the original site.

Your healthcare provider also might grade a tumor based on how likely it is to spread.

  • Grade 1 (low grade): The tumor cells look a lot like normal cells and aren’t multiplying or growing quickly.
  • Grade 2 (intermediate grade): The cells are becoming more abnormal and multiplying faster.
  • Grade 3 (high grade): The cells are significantly abnormal and are multiplying quickly.

Management and Treatment

What are the options for carcinoid tumor treatment?

Treatment may involve a combination of strategies, including:

  • Somatostatin analogs: These medications, such as octreotide, can slow the production of hormones, gastric acid and other secretions.
  • Surgery: Surgery to remove the tumor may cure localized disease.
  • Chemotherapy: Chemotherapy isn’t as effective against GI cancers as it is against other cancers. But it may be used for carcinoid tumors that have spread.


How can I reduce my risk of carcinoid tumors?

There aren’t any known ways to prevent carcinoid tumors. But scientists suspect smoking increases the risk of this type of cancer. Avoiding tobacco products or quitting smoking may help prevent the disease.

Outlook / Prognosis

What is the survival rate for carcinoid tumors?

Carcinoid tumors generally have a better outlook than other types of cancer. But prognosis depends on many factors, including:

  • Effectiveness of treatments.
  • How advanced the cancer is.
  • How aggressive the cancer is
  • Location of the tumor and any metastasis.
  • Your age and overall health.

Are carcinoid tumors fatal?

Carcinoid, or neuroendocrine, tumors can be life-threatening, particularly when cancer spreads to distant areas of your body. Metastatic (spread out) disease has a poorer prognosis than localized disease.

Living With

How do I take care of myself after treatment for a neuroendocrine tumor?

Carcinoid tumors can come back, even after successful treatment. You should have regular follow-up appointments to check for signs and symptoms of a neuroendocrine tumor. Catching cancer early can improve treatment options and effectiveness.

If you have a carcinoid tumor, ask your healthcare provider for a detailed plan for treatment and beyond, including:

  • Any tests you should have and when.
  • Best treatment options for your situation.
  • List of potential side effects from those treatments.
  • Schedule for follow-up exams and tests after treatment is completed.
  • When to call your healthcare team.
  • Ways to adjust your diet to improve symptoms or your overall health.


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