Definition of Gastrointestinal stromal tumors (GISTs)
Gastrointestinal stromal tumors (GISTs) are tumors of the digestive tract that most often occur in the stomach or upper part of the small intestine. GISTs also may be found in the esophagus, large intestine and anus. GISTs occur most often in middle-aged and older adults. GISTs are rare in children. GISTs start in the cells of your digestive tract that send signals that cause digestive organs to contract. These contractions help move food and liquids through your digestive system.