Imatinib (Glivec/Gleevec), an orally administered drug initially marketed for chronic myelogenous leukemia based on bcr-abl inhibition, also inhibits both c-KIT tyrosine kinase mutations and PDGFRA mutations other than D842V, and is useful in treating GISTs in several situations. Imatinib has been used in selected neoadjuvant settings. : 23  In the adjuvant treatment setting, the majority of GIST tumors are cured by surgery, and do not need adjuvant therapy. An exception to this is where the anatomical position of the tumour means that surgery is technically difficult or complex. For example, rectal GIST often requires radical surgery to achieve complete resection, involving abdominoperineal resection and permanent stoma. In these situations, the use of neoadjuvant imatinib can significantly decrease both tumour size and mitotic activity, and permit less radical sphincter-preserving surgery.A substantial proportion of GIST tumors have a high risk of recurrence as estimated by a number of validated risk stratification schemes, and can be considered for adjuvant therapy. The selection criteria underpinning the decision for possible use of imatinib in these settings, including a risk assessment based on pathological factors such as tumor size, mitotic rate and location, can be used to predict the risk of recurrence in GIST patients. Tumors <2 cm with a mitotic rate of <5/50 HPF have been shown to have lower risk of recurrence than larger or more aggressive tumors. Following surgical resection of GISTs, adjuvant treatment with imatinib  reduces the risk of disease recurrence in higher risk groups.
Unlike GISTs at other ages, pediatric GISTs are more common in girls and young women. They appear to lack oncogenic activating tyrosine kinase mutations in both KIT and PDGFRA. Pediatric GISTs are treated differently from adult GISTs. Although the generally accepted definition of pediatric GIST is a tumor that is diagnosed at the age of 18 years or younger, "pediatric-type" GISTs can be seen in adults, which affects risk assessment, the role of lymph node resection, and choice of therapy. Citations
General sources
de Silva CM, Reid R (2003). "Gastrointestinal stromal tumors (GIST): c-KIT mutations, CD117 expression, differential diagnosis and targeted cancer therapy with Imatinib" (PDF). Pathol Oncol Res. 9 (1): 13–9. doi:10.1007/BF03033708. PMID 12704441. S2CID 3814815. Kitamura Y, Hirota S, Nishida T (Apr 2003). "Gastrointestinal stromal tumors (GIST): a model for molecule-based diagnosis and treatment of solid tumors". Cancer Sci. 94 (4): 315–20. doi:10.1111/j.1349-7006.2003.tb01439.x. PMID 12824897. S2CID 31070671. External links
GIST Cancer UK
Surgery Questions in GIST ESUN (August 15, 2006)
SPAEN (Sarcoma Patients EuroNet) - European Network of Sarcoma, GIST and Desmoid Patient Advocacy Groups
GIST Support International
Life Raft Group International GIST Advocacy Organization
American Cancer Society Patient Guide to GIST tumors. Cancer.Net: Gastrointestinal Stromal Tumor