Gastrointestinal stromal tumors (GISTs) belong to a group of cancers called soft tissue sarcomas. Sarcomas are a rare type of cancer that can occur in connective tissues, bones, muscles, fat, nerves, blood vessels, and cartilage. Sarcomas are derived from the general class of cells known as "mesenchymal cells".

Although the exact incidence is still somewhat unclear, it is now estimated that, in the United States, between 3,000 and 5,000 people each year develop GISTs. GISTs occuring in young patients (under age 18) is much rarer, occuring in perhaps 1% to 2% of all GIST patients 1, 2. The incidence of pediatric GIST occuring in young adults is not well characterized, however data from the LRG patient registry suggests that a significant portion of female patients diagnosed between the age of 18 and 35 may have pediatric-type GIST. In the LRG registry, about 10% of the members were diagnosed between the age of 18 and 35. This age group appears to be a mixture of adult type GIST and pediatric type GIST. As better methods of identifying pediatric-type GIST (such as routine staining for the SDHB protein) enter clinical practice, the reported number of pediatric-type GIST cases will almost certainly rise.

Also the the LRG story, "Understanding pediatric GIST may provide important clues".

1. Gastrointestinal Stromal Tumors in Children and Young Adults.
A Clinicopathologic, Molecular, and Genomic Study of 15 Cases and Review of the Literature. J Pediatr Hematol Oncol Volume 27, Number 4, April 2005. Sonam Prakash, MD, Lisa Sarran, MS, Nicholas Socci, PhD, Ronald P. DeMatteo, MD, Jonathan Eisenstat, MD, Alba M. Greco, MD, Robert G. Maki, MD, PhD,{ Leonard H. Wexler, MD,k Michael P. LaQuaglia, MD, Peter Besmer, PhD, and Cristina R. Antonescu, MD

2. Gastrointestinal Stromal Tumors of the Stomach in Children and Young Adults
A Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of 44 Cases With Long-Term Follow-Up and Review of the Literature. Am J Surg Pathol Volume 29, Number 10, October 2005 Markku Miettinen, MD,* Jerzy Lasota, MD,* and Leslie H. Sobin, MD†