Correlation between spiral CT and PET in patients with advanced GIST refractory to high-dose imatinib: A GEIS study

10553 Background: Small changes in tumor size or density on computed tomography (CT) are sensitive and specific methods to assess response of GISTs and correlates well with positron emission tomography with 18F-Fluorodeoxyglucose (FDG-PET) in untreated GIST patients (pts). Despite of it, there is inconsistent prospective data in imatinib (IM) refractory disease. Methods: This multicenter phase I-II study prospectively evaluated 26 pts with metastatic high-dose IM refractory GISTs treated with doxorubicin 15 - 20 mg/m2/weekly per 4 cycles, followed by IM maintanance (400mg p.o.qd). CT and FDG-PET were performed at baseline and after 2 months of therapy. Response rate was assessed by RECIST criteria by Principal Investigator (PI). CT and FDG-PET (EORTC criteria) were reviewed by two experts in abdominal CT (AR) and one expert on Nuclear Medicine in one Institution. Results: Tumor density measurements were not assessed on CT because some studies were not available in DICOM format and different tube currents ...