Evolving Understanding of Gastrointestinal Stromal Tumors

The diagnosis and management of gastrointestinal stromal tumors (GISTs) have evolved substantially over the past 20 to 30 years. Prior to 1983, GISTs were thought to be leiomyosarcomas of the GI tract, said Anthony Paul Conley, MD. The discovery of the KIT oncoprotein and mutations in the KIT gene led to a greater understanding. Also, molecular testing has helped identify several types of GISTs, adds Conley.

Years ago, researchers and clinicians thought that GISTs originated primarily from smooth muscle, explains Robert Andtbacka, MD. Now, it is understood that they originate from pacemaker cells. This dramatically changed the way tumors are classified, Andtbacka notes. Tumors that originate from the smooth muscles constitute the minority of the tumors in the GI tract. Approximately 95% of GISTs express c-KIT, adds Andtbacka.

The most common place that GISTs arise is in the stomach, and they tend to be submucosal, according to Syma Iqbal, MD. Patients may present with nonspecific GI-related symptoms, which leads to a diagnostic workup. Endoscopic ultrasound-guided fine-needle aspiration may be used to help make a definitive diagnosis, she adds.