Diagnosis of Gastrointestinal Stromal Tumor

Executive Summary

Different tests are available for gastrointestinal stromal tumor diagnosis development, depending on signs and symptoms, age and health status, types of tumor, and earlier medical tests. Physical examination, imaging tests, and biopsies are the diagnostic approaches for eye cancer diagnosis. Most common gastrointestinal stromal tumor diagnoses include imaging tests such as Computed tomography (CT or CAT) scan, Endoscopy/endoscopic ultrasound, Magnetic resonance imaging (MRI), and Positron emission tomography (PET) or PET-CT scan. Depending on the results of imaging scans, the doctor may suggest a biopsy or surgery. Other common diagnostic approach includes tumor pathology and molecular testing of the tumor.

Diagnosis of Gastrointestinal Stromal tumor

Many tests help in diagnosing cancer. Also, tests also help to learn if the gastrointestinal tumor has spread to parts other than where it started. The spread of the tumor to other regions is metastasis and is rare for primary brain tumors. 

A biopsy is a sure way to know if you have cancer in a particular part or organ of the body for most types of cancer ^​1​.

Imaging tests can help doctors determine if the tumour is primary or if cancer has metastasized elsewhere in the body.

The different tests can be used for a person depending upon the following factors – 

• Your signs and symptoms
• The age and general health status
• The type of cancer suspected
• The result of earlier medical tests

In addition to a physical examination, the below-mentioned tests may diagnose GIST or decide the best treatment plan ^​2​.

Computed tomography (CT or CAT) scan

A CT scan is often the best test to diagnose and monitor a GIST. A CT scan clicks pictures of the body from inside using x-rays taken from different angles. A computer combines photos into a detailed, 3-dimensional image that shows abnormalities or tumors. A CT scan helps to measure the tumor’s size or help doctors determine whether cancer has spread to the gut lining or the liver. Sometimes, a particular dye known as contrast medium is given before the scan to provide a better-detailed image. This dye can be given as a pill or liquid to swallow or injected into a patient’s vein.

Endoscopy/endoscopic ultrasound

An endoscopy helps the doctor see the inside of the stomach or large bowel. The doctor performs this after sedating the patients. Sedation is medication to make a patient more relaxed, calm, or sleepy. The doctor inserts a thin, lighted tube known as a gastroscope through the mouth, down the esophagus, and into the stomach and upper small bowel with an upper endoscopy. The scope is inserted through the anus with lower endoscopy to evaluate the rectum and colon visually. If abnormal areas are found, the doctor can remove a tissue sample and check it for evidence of cancer. A particular type of test called a capsule endoscopy involves swallowing a small camera. This allows apparent viewing of the small intestine. It is helpful when other diagnostic methods cannot find the cause of GI bleeding.

Endoscopic ultrasounds resemble an endoscopy, but the scope has a small ultrasound probe on the end. The probe uses sound waves to form an image of the stomach or rectum and the nearby organs. The ultrasound image helps doctors determine how far cancer has spread into nearby tissues

Magnetic resonance imaging (MRI)

An MRI uses magnetic fields, not x-rays, to produce detailed body images. A specific dye known as contrast medium is given before the scan to create a better picture. 

If a tumor (also called a mass or nodule) is there, the doctor will also do tests to learn if it is cancerous. A biopsy is the only sure way for the doctor to know if a body area has cancer for most types of tumors. If a biopsy is not possible, the doctor suggests other tests to help diagnose.

Biopsy

The doctor may recommend a biopsy if he founds a mass suspected of being a GIST. A biopsy removes a small part of tissue to examine under a microscope. Surgery is a separate procedure if completely removing the tumor is not possible because of its position or a patient’s health.

Depending on the results of imaging scans, the doctor may suggest a biopsy or surgery. That’s because a single biopsy may not always diagnose a Gastrointestinal Stromal Tumor. A patient may need surgery to remove the entire tumor and biopsies done in several locations of the tumor to make a diagnosis. However, you must see a team of medical and surgical oncologists experienced in treating GIST before a big surgery.

Tumor pathology – A pathologist makes a diagnosis of GIST by looking at the shape and appearance of tumor cells, doing tests for a protein called KIT and other tumor markers, and finding the mitotic count (a way of measuring how many cells are actively dividing)

Molecular testing of the tumor

Your doctor may recommend you to take laboratory tests on a tumor sample to identify proteins, specific genes, and other factors, such as tumor markers, unique to the tumor. This is molecular testing of the tumor. 

GIST most often develops due to genetic mutations or changes. This includes non-hereditary tumors. The two most commonly affected genes in GIST are KIT and platelet-derived growth factor receptor alpha (PDGFRA). A tumor may have 1 of several mutations to these genes, some more harmful than others. Different mutations have different prognoses. Prognosis is the chance of recovery. When a tumor does not have a mutation in any gene tested for, it is “wild type” (WT).

Researchers are looking for more mutations to cause GIST that may help choose a patient’s treatment plans. A protein called succinate dehydrogenase (SDH) is one of them. Another is BRAF, a gene occasionally changed in people with other types of cancer, like melanoma or colorectal cancer. The results of mutation testing may help the doctor make treatment suggestions. This could include what dose of a drug known as imatinib (Gleevec, Glivec) to use or whether no further treatment or a different drug is recommended ^​3​.

Positron emission tomography (PET) or PET-CT scan

A PET scan creates images of organs and tissues present inside the body. A small proportion of radioactive substance is injected into the patient’s body which is taken up by cells using the most energy. The cancer cells which use energy actively take up the radioactive substance, and the scanner then spots this substance to produce images of the body from inside. Doctors may use PET scans to detect the amount of sugar substance taken up by the tumor. This information helps measure how well the treatment works because sometimes Gastrointestinal Stromal Tumor do not change in size even when treatment is working.

After completing the tests for diagnosis, the doctor will analyze all the results with you. These results can help the doctor describe cancer if the diagnosis is cancer.

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