What Are Gastrointestinal Carcinoid Tumors?

Medically Reviewed by Melinda Ratini, DO, MS on November 03, 2021

Everything you eat passes through your gastrointestinal (GI) tract, which is basically a series of hollow tubes. Food goes in your mouth, down your throat, into your stomach, through your intestines, and out your anus. Along the way, different organs take what your body needs and get rid of the waste.

Gastrointestinal carcinoid tumors are a type of cancer you can get in the GI tract. They’re most common in the appendix, small intestine, and rectum, which is part of the large intestine.

They’re the most common type of neuroendocrine tumor (NET). That means they’re made of neuroendocrine cells. These cells are like a cross between a nerve cell and a cell that makes hormones. You have a ton of them in your GI tract. They help control how your body breaks down food. But when they’re in a tumor they can make extra hormones you don’t need. This may lead to problems like heart issues, flushing, and diarrhea.

These tumors usually grow slowly and might not cause any symptoms for a long time. Treatment may include removing the tumor, as well as medicine to help with symptoms.

What Causes Them?

Normally, cells grow and divide in a very orderly way. But sometimes a cell gets a glitch in its genes and grows out of control, forming a tumor. Doctors aren’t sure what causes the glitch that leads to gastrointestinal carcinoid tumors.

Women tend to get them more than men. Older people get them more than younger ones. You may also be more likely to get them if you have:

What Are the Symptoms?

Early on, you might not have any. You may only find out about it because you had imaging tests to look for some other problem.

When you do get symptoms, it’s because of the tumor’s size or the hormones it makes. You might experience:

  • Belly pain
  • Diarrhea
  • Feeling very tired
  • Pain or bleeding in your rectum
  • Trouble pooping
  • Redness or warm feeling in your face and neck (“skin flushing”)
  • Throwing up or upset stomach
  • Weight loss for no reason

Because the tumor may make hormones, it can also lead to other problems like carcinoid syndrome. This may cause a number of symptoms, like skin flushing, constant diarrhea, fast heartbeat, and difficulty breathing.

How Will My Doctor Test for It?

First, they’ll ask you about your symptoms and general health. Then, they’ll do a physical exam.

Your doctor might also order the following:

  • Biopsy. He'll remove a sample of the tumor for testing. This is usually done with a needle or surgery.
  • Blood and urine tests. These look for levels of hormones or proteins that could be a sign of a tumor.

Your doctor may also use standard imaging, such as a CT scan, PET scan, MRI, or X-ray to find out where the tumor is and if the cancer has spread. Or they might use one of these tests:

  • MIBG scan. Your doctor injects you with a substance called MIBG. This is similar to the hormone norepinephrine, which acts as a stress hormone and neurotransmitter. MIBG is combined with a radioactive material that lets your doctor see how much MIBG your body absorbs. If your body soaks up a high level of the substance, it could be a sign of a tumor.
  • OctreoScan. This is just like the MIBG scan, but you get a substance called octreotide (it also contains radioactive material). If your body absorbs a lot of it, you may have a tumor.
  • Endoscopy. This procedure uses scopes that have a camera on the end. They let your doctor see inside your body. You may get an upper endoscopy to check your throat and stomach or a colonoscopy to look at your colon. Your doctor can also place a camera on a pill to check your small intestine.

How Is It Treated?


This depends on the size and where it’s located. Your age, overall health, the kind of hormones the tumor is making, and where the cancer is located all play a role in what treatment your doctor will recommend, as well.

Surgery. This is the most common treatment for these tumors. There are many types, but the idea for all of them is the same. Your doctor will remove the tumor and some of the area around it to make sure they remove all the cancer cells.

Radiation therapy. X-rays or other sources produce radiation to kill cancer cells. You can also get a special type of radiation as a drug. The idea is just like the MIBG scan. You take a pill that has MIBG and a radioactive substance. The tumor absorbs the MIBG, and the radiation kills it. Radiation is more often used when the cancer has spread to other parts of the body.

Hormone therapy. If the tumor can’t be removed, you may get regular shots of man-made hormones such octreotide (Sandostatin) and lanreotide (Somatuline). You may get them every month. They block the hormones made by the tumor. This can relieve some of your symptoms and slow the growth of the tumor.

Chemotherapy. Usually, drugs are used to kill the tumor if it starts to grow when you get hormone therapy. It may also be used for tumors that grow and spread quickly.

Treatment for Carcinoid Syndrome

If your tumor causes carcinoid syndrome, you’ll also need treatment for that. This typically includes hormone therapy, along with medicines to help with symptoms like diarrhea.

Show Sources


American Cancer Society: “Gastrointestinal Carcinoid Tumors.”

NIH, National Institute of Cancer: “Gastrointestinal Carcinoid Tumors Treatment (PDQ)–Patient Version.”

Mayo Clinic: “Carcinoid Tumors.”

Memorial Sloan Kettering Cancer Center: “Gastrointestinal Carcinoid Tumors.” 

The Ohio State University Comprehensive Cancer Center, The James: “About Gastrointestinal Carcinoid Tumors.”

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