: 1065   For example, some previous diagnoses of stomach and small bowel leiomyosarcomas (malignant tumor of smooth muscle) would be reclassified as GISTs on the basis of immunohistochemical staining. All GIST tumors are now considered to have malignant potential, and no GIST tumor can be definitively classified as "benign". Hence, all GISTs are eligible for cancer staging in the AJCC (7th edition) / UICC. Nonetheless, different GISTs have different risk assessments of their tendency to recur or to metastasize, dependent on their site of origin, size, and number of mitotic figures. Due to the change in definition, clinical pathways of care before the year 2000 are largely uninformative in the current era. Signs and symptoms
GISTs may present with trouble swallowing, gastrointestinal bleeding, or metastases (mainly in the liver). Intestinal obstruction is rare, due to the tumors outward pattern of growth. Often, there is a history of vague abdominal pain or discomfort, and the tumor has become rather large by time the diagnosis is made. Pathophysiology
GISTs are tumors of connective tissue, i.e. sarcomas; unlike most gastrointestinal tumors, they are nonepithelial. About 70% occur in the stomach, 20% in the small intestine and less than 10% in the esophagus. Small tumors are generally not aggressive, especially when cell division rate is slow. GIST tumors commonly metastasize to the liver (in 28% of cases) and/or to the greater omentum, lesser omentum, or mesentery (in 30% of cases).
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