increased gastrointestinal stromal tumor incidence GISTs MP:0009515 MPheno.ontology gastrointestinal stromal tumor higher than normal incidence of non-epithelial, mesenchymal tumors of the gastrointestinal tract, thought to originate from the interstitial cells of Cajal, the pacemaker cells that regulate peristalsis in the digestive tract; approximately 70% of GISTs develop in the stomach, 20% in the small intestine, and less than 10% in the esophagus, colon, and rectum; GISTs are tumors of connective tissue, i.e. sarcomas, account for 1-3% of all gastrointestinal malignancies in human, and are typically more cellular than other gastrointestinal sarcomas increased gastrointestinal tumor incidence