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A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413
Online ISSN 1827-1936
IMAGING OF THERAPY RESPONSE IN ONCOLOGY
Fuster D. 1, Ayuso J. R. 2, Poveda A. 3, Cubedo R. 4, Casado A. 5, Martínez-Trufero J. 6, López-Pousa A. 7, Del Muro X. G. 8, Lomeña F. 1, Maurel J. 9, Pons F. 1
1 Nuclear Medicine, Hospital Clínic Barcelona, Barcelona, Spain;
2 Department of Radiology, Hospital Clínic Barcelona, Barcelona, Spain;
3 Medical Oncology, Instituto Valenciano de Oncología, Valencia, Spain;
4 Medical Oncology, Hospital Puerta de Hierro, Madrid, Spain;
5 Medical Oncology, Hospital Clínico Madrid, Madrid, Spain;
6 Medical Oncology, Hospital Miguel Servet, Zaragoza, Spain;
7 Medical Oncology, Hospital Sant Pau, Spain;
8 Medical Oncology, Institut Català d’Oncologia, Barcelona, Spain;
9 Medical Oncology, Hospital Clínic Barcelona;
ID IBAPS, CIBEREHD
AIM: The aim of this study was to evaluate the utility of positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) in monitoring response in refractory GIST.
METHODS: This multicenter study prospectively evaluated 21 patients with locally advanced and/or metastatic GIST refractory to with high-dose imatinib (800 mg/day) treated with doxorubicin 15-20 mg/m2/weekly for 4 cycles, followed by imatinib maintenance (400 mg/day). CT and FDG-PET were performed at baseline and after completion of therapy.
RESULTS:Mean baseline tumor size on CT was 5.9 cm. Median progression-free survival (PFS) was 219 days (range 62-1108). Three out of 21 patients (14%) had partial responses (PR) under RECIST criteria, 12 patients (57%) remained stable (SD) and 6 showed progression (PD) of the disease during treatment (29%). Six patients had PR by FDG-PET, 15 showed SD (n=9) or PD (n=6) based on EORTC criteria. Patients with a PFS <6 mo showed a significantly higher ∑SUVmax at baseline (26.04±13.4) than those with PFS≥6 mo (9.82±5.0) (P<0.05). A correlation was found between PET response and PFS: PR 14±6.1 mo, SD 5.5±0.8 mo and PD 3.5±4.1 mo (P<0.05). A residual SUVmax <5 after treatment correlated with improved PFS (314±315 days vs 131±91 days) (P<0.01). Survival curves showed a significant association between PET response and PFS (P<0.05). Patients with wild-type genotype KIT (KIT-WT) showed a significantly lower baseline SUVmax (5.36±1.4) than non-WT KIT (8.40±3.6) (P<0.05).
CONCLUSION:FDG-PET is useful in assessing response of GIST refractory to imatinib and correlates with the presence of KIT-WT. Baseline ∑SUVmax can predict response to treatment in this series.