Gastrointestinal Stromal Tumor (GIST)

A gastrointestinal stromal tumor (GIST) is a type of tumor that occurs in the digestive tract, most commonly in the stomach or small intestine. GISTs are rare, accounting for approximately 1-3% of all gastrointestinal tumors.

Causes and Risk Factors

The exact cause of GISTs is not fully understood, but they are thought to arise from the interstitial cells of Cajal or their precursors. These cells are part of the autonomic nervous system and play a role in regulating digestive tract function. Mutations in certain genes, such as KIT or PDGFRA, can contribute to the development of GISTs.

Symptoms

The symptoms of GISTs can vary depending on the location and size of the tumor. Common symptoms include:

• Abdominal pain or discomfort
• Bleeding or blood in the stool
• Anemia or low red blood cell count
• Weight loss or loss of appetite
• Nausea or vomiting
• Feeling full after eating only a small amount of food

Diagnosis

The diagnosis of GISTs typically involves a combination of imaging tests and biopsy. Imaging tests may include:

• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Endoscopy or colonoscopy
• Ultrasound

A biopsy involves removing a sample of tissue from the tumor and examining it under a microscope for abnormal cells.

Treatment

The treatment of GISTs depends on the size, location, and stage of the tumor. Treatment options may include:

• Surgery to remove the tumor
• Targeted therapy with medications such as imatinib or sunitinib
• Chemotherapy
• Radiation therapy

Prognosis

The prognosis for GISTs varies depending on the size, location, and stage of the tumor. Generally, smaller tumors that are completely removed surgically have a better prognosis than larger tumors or those that have spread to other parts of the body.

Stages of GIST

GISTs are typically staged using the American Joint Committee on Cancer (AJCC) staging system, which takes into account the size and location of the tumor, as well as whether it has spread to lymph nodes or distant sites. The stages of GIST are:

• Stage I: Small tumors that have not spread
• Stage II: Medium-sized tumors that have not spread
• Stage III: Large tumors or those that have spread to lymph nodes
• Stage IV: Tumors that have spread to distant sites

Follow-up Care

After treatment for a GIST, regular follow-up care is important to monitor for recurrence or metastasis. Follow-up care may include:

• Regular imaging tests such as CT scans or MRI
• Endoscopy or colonoscopy
• Blood tests to check for tumor markers