Advanced Gastrointestinal Stromal Tumors: Historical Perspective, Future Directions - Episode 2
Initial studies with imatinib in patients with unresectable or metastatic gastrointestinal stromal tumors (GISTs) showed a response rate of more than 50%, which is dramatically different than what has been observed with chemotherapy, states Robert Andtbacka, MD. Prior to the availability of imatinib, median overall survival for patients with GIST was approximately 19 months and recurrence rates were about 60%, according to Anthony Paul Conley, MD.
Imatinib is a tyrosine kinase inhibitor that works by blocking the KIT oncoprotein, and represents the biggest advance for care in patients with GISTs, Conley adds. Diagnostics, imaging, and surgical modalities have also seen improvements. Imaging may involve CT scans or MRI. Responses to imatinib may be seen earlier on PET imaging, according to Conley.
When surgery is performed, the goal is complete gross resection, including negative microscopic margins. Endoscopic procedures, which should be reserved for patients who have small to intermediate GISTs, are best performed in high-volume centers by surgeons who have expertise in the disease, notes Conley. With GIST, the resection margins can be much smaller than in adenocarcinomas of the GI tract, says Andtbacka. Also, GIST, unlike adenocarcinomas, rarely metastasize through the lymphatic system.