Diagnosing Gastrointestinal Stromal Tumors (GIST)

About Gastrointestinal Stromal Tumors (GIST)

At Penn Medicine, patients with gastrointestinal stromal tumors (GISTs) receive their care from a multidisciplinary team of nationally recognized experts in the diagnosis, treatment and research of gastrointestinal cancer.  

Gastrointestinal stromal tumors (GISTs) are a type of soft tissue tumor. GISTs are very rare tumors that start in special cells in the wall of the GI tract, called the interstitial cells of cajal. These cells, often called the “pacemaker cells,” regulate body processes like digestion and send signals to the muscles within the gastrointestinal tract to expand and contract, moving food and liquid through the digestive system.

GISTs can occur anywhere within the digestive tract, but are found most frequently in the stomach or small intestine.

Penn Medicine’s multidisciplinary approach to cancer diagnosis and treatment provides better outcomes and gives patients with GIST access to the most advanced treatment, surgical techniques and clinical trials.

Because navigating a cancer diagnosis and treatment options can be difficult, patients who wish to connect with a cancer specialist at Penn Medicine can speak with a cancer nurse, who can help them make an appointment with the right physician.

To connect with a cancer nurse at Penn Medicine, patients should call 800-789-PENN.

Read more About Gastrointestinal Stromal Tumors (GIST)

Diagnosing Gastrointestinal Stromal Tumors (GIST)

An accurate cancer diagnosis from trusted cancer specialists is the first step in getting personalized treatment options to treat gastrointestinal stromal tumors (GISTs).

Patients who choose Penn Medicine’s Abramson Cancer Center, benefit from a multidisciplinary team of cancer specialists including gastroenterologists, radiologists, pathologists and surgeons who work together to provide a diagnosis and treatment plan custom designed for each patient with GISTs.

Cancer specialists at Penn Medicine are highly experienced in using the most advanced techniques for diagnosing gastrointestinal stromal tumors and are actively researching better and more precise ways to detect GISTs.

Navigating a cancer diagnosis and treatment options can be difficult, patients who wish to connect with a cancer specialist at Penn Medicine can speak with a cancer nurse, who can help them make an appointment with the right person. Penn Medicine’s contact center has experienced cancer nurses available and ready to guide patients in finding the cancer specialist right for them.

To connect with a cancer nurse at Penn Medicine, patients should call 800-789-PENN (7366).


Screening for GIST

Currently, there are no recommendations for screening the general public for GIST, such as mammograms or colonoscopies. However, people who are at increased risk for GIST should talk to their physicians about anal cancer screening.

GISTs may be found early by chance, such as during another examination like an endoscopy. Rarely, a GIST may be seen on an imaging test like a CT scan is performed for other reasons.

Diagnostic Tools for GIST

Penn Medicine’s multidisciplinary treatment team includes nationally recognized pathologists and radiologists who are experts at finding and diagnosing cancer.

If physicians suspect cancer, they might perform or order one or more of these tests to diagnosis and stage GISTs:

  • Medical history and physical exam. A physician feels the abdomen for swelling, fluid or other changes, and checks for enlarged lymph nodes.
  • Imaging tests. Pictures of the inside of the body can help find out whether a suspicious area might be cancerous, to learn how far cancer may have spread, and to help determine if treatment is working.
    • Upper endoscopy. Endoscopy allows the doctor to see the lining of the upper digestive system with a thin, lighted, flexible tube called an endoscope. The patient may be sedated as the tube is inserted through the mouth, down the esophagus, and into the stomach and small bowel. If an abnormality is found, a biopsy is performed.
    • Endoscopic ultrasound. An ultrasound uses sound waves to create a picture of the internal organs. This procedure is often done at the same time as the upper endoscopy. The endoscopic ultrasound (EUS) can show the extent of tumor wall involvement in the wall of and outside the GI tract, as well as enlarged lymph nodes, which may indicate a tumor or advanced disease. Endoscopic ultrasound also allows aspiration of cells from sites within the GI tract wall as well as from structures outside the GI tract such as lymph nodes. EUS-guided aspiration is usually the least invasive way of obtaining cells for diagnosis.
    • Computed tomography (CT) scan. A CT scan creates a 3-D X-ray of the inside of the body. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. A CT scan is used to see if the tumor has spread to the liver and to detect carcinoid tumors in lymph nodes behind the abdomen. Sometimes, a contrast medium (dye) is used to provide better detail.
    • Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body before the scan. The tumor absorbs the radioactive substance and the scanner detects the substance to produce images.
    • Magnetic resonance imaging (MRI). Magnetic fields are used to create detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.
    • Colonoscopy. Most colon and rectal cancer is found through a colonoscopy. A colonoscopy is a procedure done under sedation.  The physician places a thin, tube-like instrument with a light and a lens for viewing inside the rectum and colon. The scope may also have a tool to remove polyps or tissue samples, which are checked for cancer in a lab.
    • Double balloon enteroscopy. A technique similar to an upper endoscopy and colonoscopy, double balloon endoscopy has the added benefit of inserting a scope down through the mouth or up from the colon. Two balloons help anchor the scope to the intestine as it inches along so it can travel a greater distance, allowing visualization of most, if not all of the small intestine.
    • Capsule endoscopy. Video capsule endoscopies or "wireless" endoscopies help diagnose small bowel diseases or disorders. Patients swallow a capsule that contains a tiny camera and wear a data recorder. As the capsule makes its way through the digestive system, it transmits up to two pictures per second for up to eight hours. The capsule is excreted normally and painlessly usually within 10 to 48 hours
  • Biopsy. When other tests find a change that is possibly cancer, a sample of the suspicious area is removed and viewed under a microscope. A biopsy is the only way to tell if cancer is really present.
    • Fine-needle aspiration biopsy. Fine-needle aspiration (FNA) is the least invasive method of biopsy and it usually leaves no scar. An injection of local anesthesia numbs the area before the surgeon or radiologist uses a thin needle with a hollow center to remove a sample of cells from the suspicious area. Imaging studies such as ultrasound are used to guide the needle to the right location.
  • Lab tests. Lab tests can help a physician diagnose cancer, determine current organ function, learn how other organs may be affected, and look for signs of reoccurrence.

Staging GIST

Staging is a way of describing cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's chance of recovery.

Physicians at Penn Medicine use the TNM staging system:

T Stage

The T stage represents the extent of the primary tumor itself.

  • TX: Primary tumor cannot be assessed
  • T0: No evidence of primary tumor
  • T1-4: Increasing degrees of size, number or invasion of the primary tumor.

N Stage

The N stage represents the degree of the involvement of the lymph nodes.

  • NX: The regional lymph nodes cannot be assessed
  • N0: No evidence of spread to the lymph node
  • N1: Regional lymph nodes are involved with tumor

M Stage

The M stage represents whether or not there is spread of cancer to other parts of the body.

  • M0: No evidence of distant spread of the cancer
  • M1: Evidence of distant spread of the cancer including spread to non-regional lymph node chains

The “staging diagnosis” combines the T, N and M groups into four stages (Stage I-IV); some of which have subtypes (a or b) according to overall tumor characteristics.

Physicians at Penn often classify tumors by whether or not they can be resected, or surgically removed.  There are three ways physicians look at tumors:

  • Localized resectable tumors: Tumor can be completely removed by surgery. This includes most stage I and some stage II cancers in the TNM system.
  • Localized unresectable tumors: Cancers that have not spread to the lymph nodes or distant organs, but cannot be completely removed by surgery are classified as localized unresectable. This includes some early stage cancers, as well as stage IIIA and IIIB cancers in the TNM system.
  • Advanced tumors: Cancers that have spread to lymph nodes or other organs are classified as advanced. These include stage IIIC and stage IV cancers in the TNM system. Most advanced tumors cannot be treated with surgery.

In the case of gastrointestinal stromal tumors, the mitotic rate is also measured. The mitotic rate, described as either low or high, is a measure of how fast the cancer cells are growing and dividing. A low mitotic rate predicts a better outcome.

Gastrointestinal Stromal Tumor (GIST) Treatment

Following the diagnosis and staging of GISTs, cancer specialists at Penn’s Abramson Cancer Center develop a personalized treatment plan. Penn’s treatment options for GISTs include:

  • Surgery
    • Local excision
    • Low anterior resection
    • Liver resection
    • Radiofrequency ablation
  • Radiation therapy
  • Chemotherapy and biologic therapies
    • Targeted therapies
  • Clinical trials
  • Other treatments
    • Integrative medicine and wellness
    • Palliative care
    • Penn Home Care and Hospice

Because navigating a cancer diagnosis and treatment options can be difficult, patients who wish to connect with a cancer specialist at Penn Medicine can speak with a cancer nurse, who can help them make an appointment with the right physician.

To connect with a cancer nurse at Penn Medicine, patients should call 800-789-PENN (7366).

Read more Gastrointestinal Stromal Tumor (GIST) Treatment

Gastrointestinal Stromal Tumor (GIST) Survivorship

There are more than 12 million cancer survivors living and thriving today as a result of advances in cancer treatment. However, cancer treatments can result in physical, emotional and financial complications long after the therapy is complete. Survivorship programs at Penn Medicine are a distinct phase of gastrointestinal stromal tumor (GIST) care and are designed to help patients' transition from their cancer treatment routine to a post-cancer care lifestyle.

Read more Gastrointestinal Stromal Tumor (GIST) Survivorship


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