Gastrointestinal Stromal Tumors (GISTs)

Gastrointestinal stromal tumors (GISTs) result from mutations of a growth factor receptor gene, C-KIT. Some are caused by previous radiation therapy to the abdomen for other tumors.

Tumors are slow growing, and malignant potential varies from minimal to significant. Most (60 to 70%) occur in the stomach, 20 to 25% in the small bowel, and a small number in the esophagus, colon, and rectum. Average age at presentation is 50 to 60.

Symptoms of GISTs vary with location but include bleeding, dyspepsia Dyspepsia Dyspepsia is a sensation of pain or discomfort in the upper abdomen; it often is recurrent. It may be described as indigestion, gassiness, early satiety, postprandial fullness, gnawing, or burning... read more , and obstruction.

Diagnosis of GISTs is usually by endoscopy, with biopsy and endoscopic ultrasonography for staging.

Treatment of GISTs is surgical removal. The tyrosine kinase inhibitor imatinib can be used when tumors are positive for the KIT protein CD117; it is effective for patients with unresectable and/or metastatic malignant GISTs and also as adjuvant treatment following resection in adults (1 Treatment reference Gastrointestinal stromal tumors are tumors of the gastrointestinal tract derived from mesenchymal precursor cells in the gut wall. Gastrointestinal stromal tumors (GISTs) result from mutations... read more ). For imatinib-refractory tumors, sunitinib and regorafenib can be used.

Avapritinib, another tyrosine kinase inhibitor, should be used as first-line therapy for patients with a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations.