What is GIST (gastrointestinal stromal tumor)?

Introduction and incidence

GIST (gastrointestinal stromal tumor) is a rare tumor that arises in the wall of the gastrointestinal tract. It most commonly occurs in:

• the stomach (approximately 60%)

• the small intestine

• less commonly in the esophagus, colon, or rectum

Unlike most tumors of the gastrointestinal tract, GIST does not originate from the mucosa (the inner lining), but from specialized cells located within the wall of the digestive organs. Histologically, GIST belongs to a group of tumors known as sarcomas.

Risk factors

Unlike many other tumors, GIST does not have clearly defined “classic” risk factors such as smoking, diet, or lifestyle.

In most cases, GIST develops spontaneously, without a clear cause.

The most common underlying cause is mutations in the KIT or PDGFRA genes. These mutations occur during a person’s lifetime (they are not inherited) and lead to uncontrolled cell growth.

In a small number of cases, GIST may be associated with genetic syndromes such as Neurofibromatosis type 1 and Carney-Stratakis syndrome. In these cases, GIST may occur at a younger age and is often associated with multiple tumors.

GIST most commonly occurs after the age of 50 and is rare in younger individuals. It is slightly more common in men, although the difference between sexes is not significant.

Signs, symptoms and diagnosis

GIST often does not cause symptoms for a long time.

The most common signs include:

• abdominal pain or discomfort

• a feeling of fullness

• gastrointestinal bleeding (black stools or anemia)

• fatigue

• less commonly – sudden pain due to tumor rupture

  
  

Many GISTs are discovered incidentally (for example, on CT scan or during gastroscopy). Diagnosis is established through a combination of imaging methods (CT, MRI), endoscopy (gastroscopy, colonoscopy), and tumor biopsy. GIST almost always carries a mutation in the KIT or PDGFRA genes, which is confirmed by immunohistochemistry (CD117 / DOG1).

Treatment

Treatment depends on the stage of the disease.

If the tumor is localized (confined to one site), surgery is the main treatment and in some patients can lead to cure on its own. Depending on the risk of recurrence (which is influenced by tumor aggressiveness, location, size, and other factors), postoperative (adjuvant) targeted therapy may be recommended.

If the tumor is not operable or has spread, the most important drug and first-line treatment is the targeted therapy imatinib. It works by blocking the signal that drives tumor growth.

Other drugs used in later lines of treatment include sunitinib, regorafenib, and ripretinib. Importantly, even in metastatic disease, it is often possible to control the disease for a long time with therapy.

Unlike many other tumors, chemotherapy is generally not effective in GIST.

Prognosis

How dangerous is GIST? This depends on tumor size, growth rate (mitotic activity), and location. There are low-risk GISTs (slow-growing) and high-risk GISTs (with a higher chance of recurrence).

Today, GIST is one of the more “successful stories” in oncology, as effective targeted therapy exists, and many patients live for years with a good quality of life. In smaller tumors, surgery often leads to complete cure.

It is important to:

• regularly monitor the disease

• take therapy as prescribed

• stay in contact with your oncologist

When should you see a doctor? If you have:

• unexplained anemia

• black stools

• persistent abdominal pain

• unexplained weight loss

further evaluation is necessary.

In conclusion, GIST is a rare but specific tumor that is now successfully treated, particularly thanks to targeted therapy.

The most important steps are:

• making an accurate diagnosis

• performing genetic analysis of the tumor

• starting appropriate treatment on time

Additional interesting facts

GIST tumors often do not cause symptoms for a long time and can therefore grow quite large. For example, one of our patients, who was later successfully treated, initially had an abdominal GIST measuring as much as 30 cm in diameter at the time of diagnosis.

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