Gastrointestinal stromal tumors (GISTs)

Gastrointestinal stromal tumors (GISTs) are the cancers of the soft tissues of the gastrointestinal tract. They can occur in any part of the gut. GISTs are more common in the stomach followed by small intestine, colon, and rectum. These tumors are rare and represent about 0.1-3% of all the GI cancers (gastrointestinal cancers).

Symptoms

Most often, people with GIST do not exhibit any symptoms or signs. If symptoms occur, they may include:

  • Nausea and vomiting
  • Bowel obstruction
  • Early satiety and bloating
  • Pain or discomfort in the abdomen
  • A mass in the abdomen which can be felt with hands
  • Fatigue due to anemia (associated with bleeding in the intestine)
  • Vomiting blood or blood in the stools

Treatment

Localized tumors: Treatment involves complete surgical resection. It needs to be done very carefully to prevent rupture of the tumor and dissemination into the abdomen. Some of the tumors may be treated with laparoscopic surgery.

Adjuvant therapy with imatinib may be given to delay the recurrence after the resection.

Radiation therapy is often not used in the treatment of GISTs. It can be used to relieve only the associated symptoms.

Advanced tumors: Some metastatic GISTs are resectable. But if they are not resectable, then imatinib (tyrosine kinase inhibitor) is recommended. It can control up to 70-85% of the advanced GISTs. The other kinase inhibitor which is approved for advanced GISTs is sunitinib.

Chemotherapy is not effective for GISTs and hence it is not recommended.

Causes

Most of the GISTs develop sporadically, i.e. without a known reason. Usually, a tumor is produced when healthy cells grow and divide uncontrollably, forming a mass. GISTs occur due to the mutations in the two most common genes called platelet-derived growth factor receptor alpha (PDGFRA) and KIT receptor tyrosine kinase. The resultant tumor can be benign (localized) or cancerous (spreads to other parts).

Complications

The most important complication of an untreated throat cancer is its spread to the other organs of the body. They can spread to liver, entire abdomen, lymph nodes (rare), lungs and also bones.

No laboratory test can specifically confirm if you have GIST. Your doctor will ask you to go for the following tests if you present the above symptoms:

  • Complete blood cell count
  • Coagulation profile (clotting of blood)
  • Serum chemistry studies
  • Serum albumin
  • BUN and creatinine
  • Liver function tests (amylase and lipase)

The other tests which may be required to confirm the diagnosis of GIST based on the above tests are:



Test type Purpose of the test
Endoscopic ultrasound To accurately locate the lesions on the wall of the GI tract
CT (Computed tomography) scans Gives the detailed images to locate the tumors and know its size For diagnosing and staging of GISTs
MRI (Magnetic resonance imaging) To detect if multiple tumors are present and check if they have metastasized (spread)
Biopsy A part of the suspected tissue is removed and examined under microscope to check for the specific changes associated with cancer

Doctors could not find specific risk factors other than hereditary syndromes which include:

  • Age: GIST is more common in people older than 50. The occurrence of GIST in children is very rare.
  • Gender: Men are at slightly higher risk for GIST over women
  • Heredity: GIST rarely runs in families
  • Medical conditions: Neurofibromatosis type I and Carney's triad tumor syndrome which are genetic disorders