GIST is an abbreviation for GastroIntestinal Stromal Tumour.

• Gastrointestinal means that it occurs in the digestive tract, anywhere from the oesophagus to the rectum i.e. the gullet, stomach, intestines and the like.

• Stromal indicates that the tumours occur, not in the "functioning" part of the organ but in the tissues (the stromal cells) that hold the organ in place in the body. So, for example, a GIST in or near the colon is not "cancer of the colon" because it does not occur in the
functioning part of the colon but in the tissues which support the colon. (For reference, the functioning parts of any organ are made up of so-called parenchyal cells).

•Tumour simply means that the GIST condition is producing a solid(ish) lump unlike, e.g. leukaemia.

How do GISTs affect the Body?

GISTs are malignant tumours of soft tissues in the gastro-intestinal tract (the stomach and intestines). They are a very rare kind of sarcoma. Around about 2% of tumours in the gastrointestinal area are GISTs. It has only been possible to diagnose them unambiguously for the last few years.

What effect might my GIST have on me?

This depends on how big the tumour is, how fast it is growing and where it is. If it is small, causing no problems and growing very slowly, your oncologist may decide just to watch it with regular scans, and see what happens. However, if it is growing and large, or causing discomfort or bleeding, the usual treatment would be to remove it. If this would be difficult because of where it is, then the probable treatment would be with Glivec.

How common is GIST?

There are probably between 200-900 new cases each year in the UK. GISTs mostly affect people between 55 and 65, but there are GIST patients both younger and older. There are two main definitive criteria for diagnosis: finding the location of the tumour and finding a positive c-KIT (CD 117), an enzyme receptor abnormality. Until 2001 the only treatment option was surgery. Since then, very good results have been achieved with the drug Glivec® (STI571, active ingredient Imatinib). Imatinib is considered a totally new kind of cancer drug, and is being described by scientists as possibly leading to new approaches to all cancer treatment. In spite of the high effectiveness of Imatinib, cases of resistance (progression) have been observed in some patients after two to three years. For these patients it is necessary to find new drugs, and use them in clinical trials.

Today the diagnosis of GIST has different implications from those it had even a few years ago.

• GIST can now be diagnosed unambiguously
• Scientists’ understanding of the tumours is increasing daily
• An operation and/or Glivec® offer genuine therapy options
• New drugs are being developed. One of them - Sutent - has completed clinical trials and was launched by Pfizer on 1st August 2006. Other drugs are still in the trial stage.
  

(Last updated January 2007)