Downstaging of a rectal gastrointestinal stromal tumor by neoadjuvant imatinib therapy allowing for a conservative surgical approach

Gastrointestinal stromal tumor (GIST) is a recently recognized pathology that originates from the interstitial cells of Cajal1 and is the most common mesenchymal neoplasm of the gastrointestinal tract. Although surgery is the only treatment available, it is only possible in approximately half of the cases2. This malignancy is characterized by a high risk of metastatic relapse, specifically in the liver and peritoneum. Imatinib mesylate, a tyrosine kinase inhibitor that inhibits c-kit signal transduction, is often used as a treatment for metastatic GIST. Neoadjuvant therapy is defined as a treatment administered prior to the main (usually surgical) treatment for a particular neoplasm. It is used not only to eliminate circulating tumor cells but also to reduce the size of the tumor, thereby facilitating surgery and perhaps increasing the chance of organ preservation. Since imatinib results in significant tumor shrinkage in at least 50% of treated patients,3,4 its use as a neoadjuvant treatment is logical.