The Transition of the Concept of Gastrointestinal Stromal Tumor (GIST)

Abstract

Gastrointestinal stromal tumor (GIST) is generally defined as a mesenchymal tumor that consisits of spindle-shaped or epitheloid cells, originates in the gastrointestinal tract, and immunohistochemically expresses c-kit and/or CD34, regardless of myogenic and neurogenic markers. Gastrointestinal mesenchymal tumors are generally diagnosed as the submucosal tumors. Most of these tumors were histologically diagnosed as myogenic or neurogenic tumors. However, with the development of immunohistochemistry in the 1980s, we were able to clearly distinguish between myogenic tumors and neurogenic tumors. This new ability also resulted in the development of a new concept of the tumor that could not be classified into either of them. The tumor is, in fact, GIST. However, a quarter of a century was required for the concept and the treatment of GIST to be established. Because of four breakthroughs (1. the development of immunohistochemistry, 2. the classification in Ackerman's Surgical Pathology, 3. the derivation from interstitial cells of Cajal and 4. the high efficacy of imatinib mesylate) during this time, the concept of GIST has changed greatly. On the other hand, the resistance to imatinib in GIST has gradually increased, and new problems have arisen. The further development of drugs (five kinds of drugs such as SU 11248 are undergoing clinical trials) is awaited.