Gastrointestinal Carcinoid Tumors

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Early Detection, Diagnosis, and Staging TOPICS

Signs and symptoms of gastrointestinal carcinoid tumors

As mentioned in the last section, gastrointestinal (GI) carcinoids often do not cause any symptoms and may be found when looking for causes of other problems. But some do cause symptoms that may lead to their diagnosis.

Symptoms by location of the tumor

The symptoms a person develops from a GI carcinoid tumor often depend on where it is located.

The appendix

People with tumors/cancers in their appendix often don’t have symptoms. If it is discovered, it is often when they have their appendix removed during an operation for some other problem. Sometimes, the tumor blocks the opening between the appendix and the rest of the intestine and causes appendicitis. This leads to symptoms like nausea, vomiting, and abdominal (belly) pain.

The small intestine or colon

If the tumor/cancer starts in the small intestine, it can sometimes kink or block the intestines, causing abdominal pain. This pain can be mild and last for a couple of years or more before the carcinoid tumor is found. A tumor usually needs to grow fairly large before it blocks (obstructs) the intestine. When that happens, patients have severe abdominal pain, nausea and vomiting.

Sometimes, a carcinoid can cause intestinal bleeding. This can lead to anemia (too few red blood cells) with fatigue and shortness of breath. These same problems can also happen with carcinoid tumors that start in the colon.

The rectum

Rectal carcinoid tumors are often found during routine exams, even though they can cause pain and bleeding from the rectum.

The stomach

Carcinoid tumors that develop in the stomach usually grow slowly and often do not cause symptoms. They are sometimes found during an exam of the stomach by an endoscopy looking for other things (endoscopy is described later in this section). Some can cause symptoms such as the carcinoid syndrome.

Signs and symptoms caused by hormone production by carcinoid tumors

Carcinoid tumors can release hormones into the bloodstream. This can create different problems depending on which hormones are released.

Carcinoid syndrome

About 1 out of 10 carcinoid tumors release enough hormone-like substances into the bloodstream to cause the symptoms of carcinoid syndrome. These symptoms include:

  • Facial flushing (redness and warm feeling)
  • Severe diarrhea
  • Wheezing
  • Fast heartbeat

Many patients find that these symptoms are triggered by factors such as stress, heavy exercise, and drinking alcohol. Over a long time, these hormone-like substances can damage heart valves, causing shortness of breath, weakness, and a heart murmur (an abnormal heart sound).

Not all GI neuroendocrine tumors/cancers can cause the carcinoid syndrome. For example, rectal carcinoids usually do not make the hormone-like substances that cause these symptoms.

Most cases of carcinoid syndrome occur only after the cancer has already spread to other parts of the body. Normally, blood coming from the GI tract first flows through the liver, where substances made by GI carcinoid tumors are broken down before they can reach the rest of the body. This prevents carcinoid symptoms. But if the neuroendocrine cancer spreads outside the intestine (such as to the liver or lungs), the substances it makes can enter the main bloodstream and reach other parts of the body, where it can cause symptoms.

Cushing's syndrome

Some neuroendocrine tumors/cancers may produce ACTH (adrenocorticotropic hormone), a substance that causes the adrenal glands to make too much cortisol. This can cause Cushing's syndrome, with symptoms of:

  • Weight gain
  • Muscle weakness
  • High blood sugar (even diabetes)
  • High blood pressure
  • Increased body and facial hair
  • Bump of fat on back of neck
  • Skin changes like stretch marks (called striae)

Most GI carcinoids grow slowly and produce vague symptoms that are more often caused by something else. When trying to figure out what's going on, doctors and patients are likely to explore other, more common possible causes first. This can delay a diagnosis, sometimes even for several years.


Last Medical Review: 12/31/2013
Last Revised: 12/31/2013