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A GIST (Gastrointestinal Stromal Tumor) diagnosis is typically made or ruled out based on a patient’s medical history, a comprehensive physical examination and the results of a series of tests. If a gastrointestinal stromal tumor (GIST) is suspected due to a patient’s symptoms or the outcome of a medical test that was performed for another reason, a physician may order one or more imaging tests or endoscopy exams to evaluate the interstitial cells of Cajal (ICC). GISTs develop within the ICC, which line the walls of the gastrointestinal (GI) tract. The testing method(s) used to confirm or rule out a GIST can vary based on a patient’s symptoms and other individual factors. 

Some techniques that can facilitate a GIST diagnosis include:

  • Imaging tests – Computed tomography (CT) scans, magnetic resonance imaging (MRI) scans and positron emission tomography (PET) scans can provide detailed images of the GI tract.
  • Upper endoscopy – A flexible, lighted tube (endoscope) and tiny camera are inserted through a patient’s mouth and used to project images of the upper GI tract onto a video screen. If necessary, a physician can also use the endoscope to obtain tissue samples.
  • Barium X-rays – A patient swallows a chalky solution containing barium, which coats the lining of the GI tract and makes any abnormalities easier to detect through X-rays.
  • Colonoscopy – A special type of endoscope called a colonoscope is inserted into a patient’s anus and used to project images of the colon onto a video screen. If necessary, a physician can obtain tissue samples during the same procedure.
  • Endoscopic ultrasound – An endoscope with an attached ultrasound probe generates sound waves that produce echoes, which can be converted into detailed images of the GI tract.
  • Microscopic evaluation of tissue samples obtained through a biopsy – If a mass is detected, a small sample of cells is removed for further testing by a pathologist.
  • Blood testing – Certain tests that reveal a low red blood cell count (anemia) or abnormal liver function can signal the possible presence or spread of a GIST.

After making a GIST diagnosis, a physician will usually order further testing to assess the extent of the cancer and the degree to which it has spread. This information is integral to the development of an individualized treatment plan.

Moffitt Cancer Center’s Gastrointestinal Oncology Program is a recognized leader in the diagnosis and treatment of GI cancers. No referral is needed to discuss a confirmed or possible GIST diagnosis with one of our experienced oncologists. Prospective patients can complete a new patient registration form online or call 1-888-663-3488.