Summary about Disease
Gastrointestinal stromal tumors (GISTs) are rare tumors that arise in the gastrointestinal (GI) tract, most commonly in the stomach and small intestine. They originate from specialized cells called interstitial cells of Cajal (ICCs), which are part of the autonomic nervous system and regulate GI motility. GISTs can be benign or malignant, with the malignant potential determined by factors like tumor size, mitotic rate (how quickly cells are dividing), and location.
Symptoms
GISTs can present with a variety of symptoms, depending on their size and location. Some common symptoms include:
Abdominal pain or discomfort
A palpable mass in the abdomen
Nausea and vomiting
Blood in the stool or vomit (leading to anemia)
Fatigue
Loss of appetite
Weight loss
Difficulty swallowing (if the tumor is in the esophagus)
Bleeding (which can sometimes be significant and lead to anemia) Some GISTs are asymptomatic and are discovered incidentally during imaging for other reasons.
Causes
The majority of GISTs are caused by mutations in the KIT or *PDGFRA* genes. These genes encode receptor tyrosine kinases, which are proteins involved in cell growth and division. The mutations cause these kinases to be constitutively activated, leading to uncontrolled cell proliferation and tumor formation. The exact reasons why these mutations occur are often unknown. In some rare cases, GISTs can be associated with certain genetic syndromes, such as neurofibromatosis type 1 (NF1).
Medicine Used
The primary medical treatment for GISTs involves targeted therapies that inhibit the activity of the KIT and PDGFRA kinases. The most commonly used medications include:
Imatinib (Gleevec): A tyrosine kinase inhibitor that targets the KIT and PDGFRA proteins. It is often the first-line treatment for GISTs.
Sunitinib (Sutent): Another tyrosine kinase inhibitor used when imatinib is no longer effective or if the tumor develops resistance.
Regorafenib (Stivarga): A tyrosine kinase inhibitor used when imatinib and sunitinib are no longer effective.
Ripretinib (Qinlock): A tyrosine kinase inhibitor used when other treatments have failed. It targets a broader range of KIT mutations, including some that cause resistance to other drugs. Surgical removal is often considered if possible.
Is Communicable
No, GISTs are not communicable. They are not caused by infectious agents and cannot be spread from person to person.
Precautions
Since the exact causes are largely unknown, there are no specific precautions to prevent GISTs. For individuals with genetic conditions associated with increased GIST risk (e.g., NF1), genetic counseling and regular monitoring may be recommended. Individuals undergoing treatment need to follow all instructions from the medical team regarding drug administration and monitoring for side effects.
How long does an outbreak last?
GIST is not an "outbreak" in the sense of an infectious disease. GIST is a tumor. How long the tumor is present depends on if its found early and if surgery is successful. If surgery is not possible, treatment is continued until the medication stops working or side effects are too severe.
How is it diagnosed?
Diagnosis of GIST typically involves a combination of the following:
Imaging Studies: CT scans, MRI scans, and PET scans can help visualize the tumor, assess its size and location, and determine if it has spread. Endoscopic ultrasound (EUS) can be used to obtain a biopsy of the tumor.
Biopsy: A tissue sample is taken from the tumor and examined under a microscope to confirm the diagnosis and determine the tumor's characteristics, including mitotic rate and presence of KIT or *PDGFRA* mutations. Immunohistochemistry (IHC) is used to detect the presence of the KIT protein, which is usually present in GISTs. Genetic testing is performed to identify specific mutations in *KIT* or *PDGFRA*.
Timeline of Symptoms
The timeline of symptoms can vary greatly depending on the size, location, and growth rate of the tumor. Some individuals may experience symptoms for weeks or months before seeking medical attention, while others may have no symptoms at all. In some cases, a GIST may grow slowly over a long period before causing noticeable symptoms. Acute symptoms, such as severe bleeding, can also occur suddenly.
Important Considerations
Risk Stratification: GISTs are classified into risk categories (very low, low, intermediate, and high) based on factors like tumor size, mitotic rate, and location. This helps determine the likelihood of recurrence and guide treatment decisions.
Treatment Monitoring: Regular monitoring with imaging studies is important to assess the response to treatment and detect any signs of recurrence.
Side Effect Management: Tyrosine kinase inhibitors can cause a range of side effects, so careful monitoring and management are essential.
Multidisciplinary Approach: Management of GISTs typically involves a team of specialists, including oncologists, surgeons, radiologists, and pathologists.
Clinical Trials: Individuals with GISTs may be eligible to participate in clinical trials testing new treatments.