Gastrointestinal stromal tumors: epidemiology, clinical picture, diagnosis, prognosis and treatment.

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. They originate from the myenteric ganglion cells, termed the interstitial Cajal cells. The majority, i.e. 95% of GIST, show expression of the membrane receptor protein CD117 with a tyrosine kinase activity c-kit. Gastrointestinal stromal tumors constitute less than 1% of all digestive tract tumors. They may be benign or malignant (30%), and occur in every part of the gastrointestinal tract, however the stomach is the most common localization. They develop with the same prevalence in men and in women, usually above the age of 50 years. The peak incidence is observed between the fifth and the sixth decade of life. Symptoms are not typical and depend on the localization and the tumor size. About 10-30% of GIST are completely asymptomatic, and are discovered accidentally during the endoscopy or X-rays evaluation as well as during surgical interventions performed for various reasons. The malignant tumors metastasize most commonly to the liver and peritoneum. The metastases are rarely found in the lungs, pleura and bones. The detection of GIST is based on imaging, endoscopy, histological and immunohistochemical examinations. A useful and promising diagnostic procedure is positron emission tomography. The final diagnosis is mostly based on the pathologic findings of the removed tumor. The prognosis of GIST depends on its size, mitotic activity in 50 high power fields and mucosal infiltration. Radical surgery is the best treatment of GIST.