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Cancer Health Center

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Understanding Carcinoid Tumor

Risk Factors for Carcinoid Tumors

Researchers are still learning about carcinoid tumors and what causes them. There are a few known risk factors for carcinoid tumors, and most are not factors you can control or change.

  • Genetic syndromes. People with a rare genetic syndrome called Multiple Endocrine Neoplasia, type 1 (MEN1) have a higher risk of certain tumors, including carcinoid tumors. Those with a disease called neurofibromatosis type 1 are also at higher risk for developing carcinoid tumors.
  • Gender. Women may be at slightly higher risk of developing carcinoid tumors. Researchers aren't sure why.
  • Race. Gastrointestinal carcinoid tumors are more common in African-American men and women than in Caucasians. But lung carcinoid tumors are more common in Caucasians than in people of other races.
  • Stomach conditions. Those who have a stomach condition that reduces the amount of acid in the stomach and damages the stomach have a higher risk of carcinoid tumors in the stomach.
  • Smoking. Smokers may be more likely to have certain types of lung carcinoid tumors. A recent study in Europe also found that smoking may double the risk of having a carcinoid tumor in the small intestine. But more research is needed to confirm these results.

Diagnosing Carcinoid Tumors

Because carcinoid tumors grow slowly, many are caught early, before they have had a chance to metastasize or cause symptoms. In many cases, they are found during routine tests or exams when looking for other problems.

"These tumors are often found by accident," says James Yao, MD, associate professor and deputy chair of the Department of Oncology at the University of Texas MD Anderson Cancer Center in Houston. "We may find them during a screening colonoscopy or endoscopy or because of abnormal results on a liver function test."

Sometimes the tumors are found because they are causing symptoms. If your doctor suspects a carcinoid tumor, there are a few different types of diagnostic tests to use.

  • Blood and urine tests. These simple tests are often a first step in diagnosing carcinoid syndrome. Doctors use these tests to look for the excess hormones and other substances that carcinoid tumors produce.
  • Imaging tests. Doctors may use imaging tests to take pictures of the inside of your body to locate tumors. These tests may include X-ray, CT scan, MRI, PET scan, or octreoscan. An octreoscan is especially helpful in finding carcinoid tumors. During the test, a small amount of radioactive material and a hormone-like substance that is attracted to carcinoid tumors are injected into the bloodstream. A few hours later, a special camera looks for any "hotspots" where these substances have collected.
  • Endoscopy. This is a type of test that uses a long flexible tube with a camera or ultrasound at the end to look for gastrointestinal tumors. Using various kinds of endoscopy, doctors can see almost all areas of the digestive tract, from the esophagus to the rectum.
  • Biopsy. Once the tumor has been found, your doctor may take a small piece of tissue from the tumor to look at it under a microscope. "A biopsy is essential in diagnosing carcinoid tumor," says Warner. "Until you examine the cells under a microscope you don't know for certain what type of tumor you're dealing with. It also helps us know what type of treatments the tumor will best respond to."

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