15621 Background: Sorafenib is a new potent multikinase inhibitor directed against both tumour proliferation and angiogenesis. Clinical benefit has been shown in 75% of patients with metastatic renal cell carcinoma. The aim of this study was to evaluate this new treatment with PET-CT with fluorodeoxyglucose (FDG), since the use of only CT measurements has been questioned. Methods: 10 patients (8 male, 2 female, 49–72 years) with metastatic renal cell carcinoma (9 clear cell, 1 chromophobe). All had progressive disease (8 after interferon). Sorafenib 400 mg b.i.d was given orally. FDG-PET-CT scan was performed from head-proximal thigh before treatment and after one month. Up to 6 target lesions in each patient were studied. The sum of the largest diameters was calculated from CT images for each patient. To evaluate the glucose uptake, a region of interest (roi) was designed for each leasion on the initial PET on the transverse section where the lesion appeared to be largest and/or most intense. Using the same roi for subsequent examinations the mean glucose uptake/mean cerebellar uptake was calculated. For each patient the mean change from baseline was calculated. Results: After one month of treatment the sum of tumour diameters measured by CT was mean 85% (53–110%) of the initial value. Measured by PET the mean glucose uptake at one month was mean 73% (29–100%) of the initial value. Seven patients had skeletal lesions. These were often difficult to measure on CT and only small changes were detected. Using PET the mean uptake in skeletal lesions was 77% (62–104%) at one month. Conclusions: Early effects of sorafenib treatment in metastatic renal cell carcinoma can be detected and quantified by PET-CT. Especially in skeletal lesions PET-CT exhibits considerable benefits over CT by visualizing responses otherwise missed. Future studies will reveal if a decrease in tumour glucose uptake at one month correlates with the more clinically relevant endpoints PFS and OS. [Table: see text]
Metastatic Renal Cell Carcinoma: Relationship Between Initial Metastasis Hypoxia, Change After 1 Month's Sunitinib, and Therapeutic Response: An 18F-Fluoromisonidazole PET/CT Study
