Digestive disorders

III/4.2: Epidemiology

No exact data on its epidemiology are available. It occurs more commonly than thought earlier. Its incidence is 16/1 000 000 inhabitants. In the USA 3000 to 5000 (7 to 20/1 000 000/year), in Germany 1200, and in Hungary 150 to 160 new cases of GIST are presumed yearly .

It may occur at any age, but it is the commonest between the fiftieth and sixtieth years of life. The average age of its detection is 55 to 63 years. It is rare under the age of 20 years; however its occurrence in childhood has also been reported. 20% of patients are under the age of 40 years. Metastasis formation is more common in younger patients. Both genders are affected at the same ratio. A metastasizing process is more frequently observed in male patients. No specific geographic or ethnic accumulation has been reported.

The majority of cases are sporadic. Its familial aggregations are due to inherited mutations of the KIT gene. In these families there is an increased risk of multiple gastric and intestinal GISTs; in addition hyperpigmentation of the skin, dysphagia, and tumor of the gastrointestinal autonomic nerve system (paraganglioma) may also develop. It is also more common in families with Recklinghausen’s disease.

It may occur in the entire gastrointestinal tract. It accounts for less than 3% of malignant tumors of esophagus, stomach, colon and rectum. After carcinomas and lymphomas, it accounts for 20% of tumors in the small intestine. It develops most frequently in the stomach (52 to 70%) and in the small intestine (20 to 25%, usually in the jejunum). It is less frequent in the colon, rectum (5%) or in the esophagus (<5%). In more than 80% it appears in the gastrointestinal tract, in 10% in can be found in the retroperitoneal area or in the lesser pelvis .