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Carcinoid Tumors and Carcinoid Syndrome Causes, Symptoms, and Treatments

Carcinoid tumors are rare, slow-growing neuroendocrine cancers. They often form in the digestive system but can grow elsewhere.

Carcinoid syndrome is a collection of symptoms in some people with carcinoid tumors.

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What Are Carcinoid Tumors and Carcinoid Syndrome?

What is a carcinoid tumor? Doctors define them as a slow-growing cancer of the neuroendocrine system.

There's no benign carcinoid tumor. All carcinoid tumors are cancer.

Carcinoid tumors aren't the same as other, more common gastrointestinal (GI) tract tumors. Instead, they're cancerous growths of neuroendocrine cells scattered throughout the body.

These cells release hormones into the blood that help the body function.

Carcinoid tumors are rare. They affect about four in every 100,000 adults in the U.S.

The average age of someone diagnosed with a carcinoid tumor is in their early sixties. These tumors are extremely rare in children and teens.

Carcinoid syndrome occurs in about one out of 10 people with carcinoid tumors. It happens when the cancer cells release hormones into the blood.

Carcinoid syndrome symptoms include wheezing, flushing, and diarrhea.

What are the types of carcinoid tumors?

Carcinoid tumors can grow anywhere there are cells that make hormones.

Common parts of the body where these tumors appear include the:

  • Appendix.
  • Colon.
  • Liver.
  • Lungs.
  • Pancreas.
  • Rectum.
  • Small intestine.
  • Stomach.

Doctors grade carcinoid tumors by how fast they grow.

  • Grade 1 (low-grade) tumors. These have cells that look more like normal cells and aren't growing fast. They often don't spread to other parts of the body.
  • Grade 2 (intermediate-grade) tumors. These have features in between low- and high-grade carcinoid tumors.
  • Grade 3 (high-grade) tumors. These have cells that look very abnormal and are growing faster. They may spread to other parts of the body.

What causes carcinoid tumors and carcinoid syndrome?

Doctors don't yet know what causes carcinoid tumors. They may occur because of DNA changes in a person's cells.

No one thing causes these changes. Some inherited gene changes may raise the risk of these tumors.

Carcinoid syndrome happens when the tumor releases excessive hormones into the blood.

What are carcinoid tumors and carcinoid syndrome risk factors and complications?

Doctors are still studying why and how carcinoid tumors form. But they have found some risk factors.

Carcinoid tumors and carcinoid syndrome risk factors

Most risk factors for carcinoid tumors are genetic and may include:

  • Multiple endocrine neoplasia type 1. People with this gene change have a high risk of pituitary, parathyroid, and pancreas tumors. They also have a higher risk of getting carcinoid tumors.
  • Neurofibromatosis type 1. This disease often runs in families. People who have it get benign tumors in nerves under the skin. Some people who have it form carcinoid tumors in the small intestine.
  • Other genetic syndromes. People with other gene changes may be at risk for carcinoid tumors. They include tuberous sclerosis complex, von Hippel Lindau disease, and familial small intestinal neuroendocrine tumor.

Other risk factors for carcinoid tumors are:

  • Being born female. Those born female get more carcinoid tumors than those born male.
  • Being African American. African Americans have more carcinoid tumors than other groups.
  • Smoking. People who smoke may be at higher risk.

The risk factor for carcinoid syndrome is having a malignant carcinoid tumor.

Complications of carcinoid tumors

One complication of having a carcinoid tumor is that it could spread to other organs.

Another is developing carcinoid syndrome, which can affect your heart.

How can I prevent carcinoid tumors?

Since most cases of carcinoid tumors come from gene changes, there's no way to prevent the disease. Quitting smoking may reduce your risk.

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Carcinoid Tumor and Carcinoid Syndrome Symptoms and Diagnosis

What are the symptoms of a carcinoid tumor?

Carcinoid tumors often grow slowly and may not have any symptoms. Or the carcinoid symptoms are so vague that doctors first look for more common causes.

Symptoms may also vary based on where the tumor is in the body.

Symptoms of carcinoid tumor may include:

  • Anemia.
  • Diarrhea.
  • Nausea or vomiting.
  • Pain in the belly.
  • Pneumonia.
  • Spitting up blood.

What are the symptoms of carcinoid syndrome?

When carcinoid tumors release hormones into the bloodstream, it can cause carcinoid syndrome.

Factors like stress, exercise, and drinking alcohol can trigger carcinoid syndrome symptoms, which include:

  • Fast heartbeat.
  • Flushing (redness and a warm feeling in your face).
  • Severe diarrhea.
  • Wheezing.

How do you diagnose carcinoid tumors?

To diagnose carcinoid tumors, doctors will use tests, including:

  • Barium x-rays.
  • Biopsy.
  • Blood and urine tests.
  • Colonoscopy.
  • CT scans.
  • Endoscopy.
  • MRI scans.
  • Radionuclide scans.

Doctors may arrive at a carcinoid tumor diagnosis:

  • When treating or testing for another condition.
  • During a routine colonoscopy or surgery, like removing your appendix.
  • If you have carcinoid syndrome symptoms like flushing, wheezing, and diarrhea. You would only have carcinoid syndrome if you had a carcinoid tumor.
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How Do You Treat Carcinoid Tumors and Carcinoid Syndrome?

UPMC experts use the latest techniques to diagnose and treat carcinoid tumors.

High-tech imaging studies and lab testing can help find the exact size and location of the tumor.

Surgery to treat carcinoid tumors

Surgery is the preferred treatment for carcinoid tumors when possible.

Surgeons may be able to remove the cancer entirely. They will also remove some of the surrounding tissue.

To treat carcinoid syndrome, doctors treat the tumor. Removing the tumor will stop the carcinoid syndrome symptoms, too.

Metastatic carcinoid tumor treatments

If a carcinoid tumor is large or has spread, surgery may not be an option.

Treatments for large or metastatic carcinoid tumors may include:

  • Chemotherapy. Uses strong drugs that kill fast-growing cells.
  • Radiation (sometimes with surgery). Destroys cancer cells with energy beams.
  • Radiofrequency ablation. Destroys cancer cells with heat.
  • Somatostatin analogs. Stops your body from making too many hormones. It may slow down the growth of the tumor when cancer cells have spread.
  • Targeted therapy. Uses drugs to target certain genes or proteins that help cancer cells survive.
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