A gastrointestinal stromal tumor (GIST) is a type of tumor that occurs in the gastrointestinal tract, most commonly in the stomach or small intestine. This type of tumor is thought to grow from specialized cells found in the gastrointestinal tract called interstitial cells of Cajal (ICCs) or precursors to these cells. Affected individuals can develop one or more tumors. GISTs are usually found in adults between ages 40 and 70; rarely, children and young adults develop this type of tumor.

Genetic changes in one of several genes are involved in the formation of GISTs. About 80 percent of cases are associated with a mutation in the KIT gene, and about 10 percent of cases are associated with a mutation in the PDGFRA gene. Mutations in the KIT and PDGFRA genes are associated with both familial and sporadic GISTs. Less than 10 percent of cases are SDH-deficient GISTs, which are associated with mutations or other changes in the SDHA, SDHB, SDHC, or SDHD gene. SDH-deficient GIST can be familial or sporadic. A small number of people with a GIST have mutations in other genes.

Approximately 5,000 new cases of GIST are diagnosed in the United States each year. SDH-deficient GIST accounts for about 5 to 7 percent of cases. However, GISTs may be more common than the estimate because small tumors may remain undiagnosed.

Most cases of GIST are sporadic and are not inherited. These cases are associated with a somatic mutation, which is a genetic change that occurs only in the tumor cells and occurs during a person's lifetime.

Published Date: July 14, 2021Published By: National Institutes of Health