Safety and efficacy of percutaneous radio-frequency ablation (RFA) in patients (pts) with metastatic gastrointestinal stromal tumor (GIST) with clonal evolution of lesions refractory to imatinib mesylate (IM)

Abstract

9024 Background: IM is a highly effective treatment for metastatic/unresectable GIST. Although pts may exhibit durable systemic disease control, with time clonal evolution of lesions refractory to IM emerge and require alternative treatment approaches. We have evaluated the role of percutaneous RFA in this subset of pts with single or oligoclonal progressing GIST lesions who are in good performance status. Methods: Pts with limited sites of GIST progressing despite continuation of IM were treated with CT-guided RFA. All pts had staging with CT/MRI as well as functional imaging with 18FDG PET scans, both before and after RFA. Biopsy of the target lesions was performed before RFA. Results: Nine pts treated with imatinib for a median of 25 months (m) (range 18–36 m) underwent RFA for single or limited site(s) of progressing disease. Sites of progression: 8/9 pts with liver metastases, 1/9 with soft tissue disease. 5/9 of these pts developed a new nodule within a pre-existing GIST lesion, the remaining 4/9 ha...