Because gastrointestinal carcinoid tumors do not typically cause symptoms in their early stages, these early-stage tumors may only be discovered when a patient is being examined for another condition. For example, they may be discovered during an appendectomy or when a patient is screened for colorectal cancer.

However, a physician may suspect gastrointestinal carcinoid tumors in cases of persistent abdominal pain. In diagnosing a gastrointestinal carcinoid tumor, a physician will perform a thorough physical examination and compile a comprehensive medical history. During the physical examination, the physician will look for the following symptoms:

• Abdominal mass and enlarged liver
  
• Prominent skin veins (telangiectasis)
  
• Signs of carcinoid syndrome, including:
  
  
• • Heart murmur
    
  • Wheezing
    
  • Skin flushing

Gastrointestinal carcinoid tumors often produce excess levels of the hormone serotonin that may be detected during 24-hour urinary testing. The physician will look for elevated levels of 5-hydroxyindoleacetic acid (5HIAA), a metabolic product of serotonin, in the patient’s urine sample. Patients may be placed on a restricted diet prior to such testing because certain foods and medications can cause false positives.  Blood tests may also reveal the presence of certain hormones that may indicate carcinoid syndrome.

Imaging tests may also be used to examine the gastrointestinal tract and to look for signs of intestinal obstruction or spread of the cancer. These tests may include:

• CAT scan. Uses multiple x-ray images, taken from different angles, and a computer to create three-dimensional images of internal body structures.
  
  

  

• Radionuclide imaging. Test in which tiny amounts of radioactive materials (called “tracers”) are introduced into the patient’s body. The tracers emit a type of energy called gamma rays, which are detected by special devices and converted into images of internal body structures. A type of radionuclide scan called a somatostatin receptor scintigraphy (SRS) is used to locate carcinoid tumors. A PET scan is another type of radionuclide imaging test that may be used to identify spread of the disease.
  
  
• X-ray. Creates an image of part of the body by using low doses of electromagnetic radiation. The patient may consume a barium liquid or food, or have a barium enema to create images of the digestive tract.
  
  
• MRI. Produces clear cross-sectional or three-dimensional images of the body’s tissues, even through bone and other obstructions. This produces images similar to those of a CAT scan, but in greater detail.
  
  

  

• Upper endoscopy. A thin, lighted tube called an endoscope is inserted through the mouth and esophagus into the stomach and the first part of the small intestine. This can be used to look for abnormalities in these areas.
  
  
• Colonoscopy. A thin, lighted tube called a colonoscope is inserted through the rectum into the colon to search for abnormalities.
  
  
• Biopsy. Removal of cells or tissues for laboratory analysis. Biopsies may be performed during an endoscopy or colonoscopy.

Because gastrointestinal carcinoid tumors spread so slowly, about one-half of these cancers are diagnosed at an early stage before the cancer has spread, according to the American Cancer Society.