Gastric GIST

Gastrointestinal stromal tumours were until the last decade described as leiomyomas or leiomyosarcomas and it is only with advances in molecular biology that this particular tumour has been recognized as a discrete entity. GI stromal tumours can arise anywhere in the GI tract but the stomach is the commonest site. They are mesenchymal tumours believed to originate from the interstitial cells of Cajal. They generally present as

elevated submucosal swellings that ulcerate or bleed; a number are discovered as incidental findings at endoscopy. GIST’s behave in a somewhat unpredictable manner with many appearing to be completely benign and others as an aggressive malignancy. Increased risk of malignant behavior is associated with increasing size and the number of mitoses seen within pathological specimens. GIST tend to spread through local invasion and haematogenous spread, lymph node metastases are unusual. Once diagnosed and staged through a combination of CT scanning and if available endoscopic ultrasound treatment is surgical resection. There is no role for associated lymph node dissection.

At a molecular level GIST’s are characterized by an abnormality of one of several transmembrane growth factor receptors, the commonest (85–90%) being the molecule        c-kit (CD117). Recently it has been demonstrated that the c-kit antagonist imatinib can produce very significant tumour regression of advanced GIST’s.