Gastrointestinal stromal tumor (GIST)

GIST is the most common form of sarcoma (a type of cancer that develops from the cells of the body’s connective or supportive tissues) involving the gastrointestinal tract. GIST can occur anywhere along the GI tract but is most often found in the stomach (40-70 percent of cases) or the small intestine (20-30 percent of cases).

Approximately 11 to 20 people per million worldwide are diagnosed with GIST each year and in Europe there are an estimated 15 people per million living with GIST.

GIST represents a life-threatening malignancy if the disease has spread to other parts of the body (metastasized) or is unable to be surgically removed with curative intent. GIST affects an estimated 11-20 patients per million per year worldwide.

The discovery of oncogenic KIT kinase mutations in GISTs and the introduction of kinase inhibitor therapies have led to a rapid evolution in the understanding of these tumors. It is now established that 70–80% of GISTs harbor a KIT gene mutation, that these mutations lead to the continued activation of the kinase and that mutant KIT is a clinically important therapeutic target in GIST.

Unless they are located in certain regions of the digestive system, GIST may not cause any noticeable symptoms until they reach a certain size. As a result, GIST is often not diagnosed until later stages of disease6 at which point, 10-25% of people diagnosed will have developed metastatic disease.

GIST is often diagnosed when blood is detected in the stool or vomit. Should the tumor grow large enough, it can block the passage of food to the stomach or intestine, resulting in severe abdominal pain and vomiting.

Over time, the continued blood loss will lead to anemia, or low red blood cell count, causing patients to feel tired and weak.

Treating GIST

The treatment of GIST depends on a number of factors, including the patients’ general health and the size and position of the tumor. Surgery is the main treatment option for GIST that has not spread or has only spread into nearby tissue. Tumors that are larger or located in places where the cancer may be harder to remove without causing potential health problems later on are often prescribed targeted therapies. These are known as growth inhibitors and work by blocking growth signals, preventing the GIST cells from multiplying. Chemotherapy and radiotherapy are not effective for this type of cancer and are therefore rarely used.

Three growth inihibitors have been approved for the treatment of GIST if the tumor cannot be surgically removed and/or has already spread.

Advice for patients

Each body reacts differently to medicines. Therefore it is impossible to tell which medicine works best for you. Please consult your physician.