Genetics of Gastrointestinal Stromal Tumors : A Heterogeneous Family of Tumors?

Approximately 85–90% of adult gastrointestinal stromal tumors (GISTs) harbor KIT and PDGFRA mutations. The remaining cases, including the majority of pediatric GISTs, lack these mutations, and have been designated as KIT/PDGFRA wild-type (WT) GISTs. Nearly 15% of WT GISTs harbor BRAF mutations, while others arise in patients with type I neurofibromatosis. Recent work has confirmed that 20–40% of KIT/PDGFRA WT GISTs show loss of function of succinate dehydrogenase complex. Less than 5% of GISTs lack known molecular alterations (“quadruple-negative” GISTs). Thus, it is important to consider genotyping these tumors to help better define their clinical behavior and therapy.