<qa>  What is the neoplasm of the gastrointestinal tract?Gastrointestinal stromal tumor GIST is a specific, immunohistochemically KIT mesenchymal neoplasm of the gastrointestinal tract. The identification of KIT tumor has become more important after introduction of target treatment with KIT tyrosine kinase inhibitor Imatinib mesylate Gleevec. Despite this progress, GIST patients presenting a tumor larger than 5 cm have a 10 year survival between 10 and 30. Indeed, the risk of microscopic spreading of the tumor during surgery is very high since intra-abdominal organs are in close relation to each others. To improve survival, it seemed logical to use preoperative Gleevec to reduce tumor size and improve efficacy of the surgical procedure. 