About

GIST stands for GastroIntestinal Stromal Tumour. A GIST occurs when special cells within the wall of the gastrointestinal (GI) tract change so that they grow more than they should. It is a specific type of tumour that comes under the umbrella medical term of 'sarcoma'. This can affect any part of the GI tract, from the gullet (or oesophagus) to the rectum. The most common site for these tumours is the stomach. Most often, they are picked up when tests are performed for symptoms caused by something else, such as an endoscopy for indigestion, although they can also cause a variety of symptoms, the most common of which are explained below. Compared to other types of oesophageal or gastric tumour, they have a much lower risk of spreading.

Figure 1. GIST within the stomach as seen at upper GI endoscopy. Credit: Samir Grover, 2004.

Bleeding and anaemia

Sometimes GISTs can develop an ulcer on their surface and bleed. Sometimes this bleeding is so slow that it cannot be seen. It may, however, cause enough blood loss that a person becomes anaemic. This may cause a feeling of tiredness and lethargy, and a person may get out of breath more easily than normal. In other patients, they can cause more noticeable bleeding which may resulting in vomiting up blood, or a patient's stool (or faeces) may turn very dark, smelly and become sticky like tar.

Bowel obstruction

Depending upon the size or position of the tumour, a GIST can cause a blockage to the flow of food and drink through the guts. This is more common when a GIST is either big or is located at a narrow point in the gut. If this causes a blockage, a person may develop crampy pain, bloating, nausea and vomiting, and ultimately they may stop opening their bowels. This is a relatively uncommon problem with GISTs.

Bloating or swelling

Sometimes a GIST may be diagnosed once it has grown very large when it causes bloating or swelling of the abdomen because of the amount of space it occupies inside the tummy.