The capacity of 18F-FLT PET/CT imaging to predict therapeutic response early after EOF chemotherapy in advanced gastric cancer: Comparison with 18F-FDG PET/CT imaging

Objectives The aim was to evaluate whether the therapy-induced reduction of 18F-FLT-PET/CT SUVmax (ΔSUVmax) in patients with advanced gastric cancer treated with chemotherapy of EOF scheme could predict therapeutic response and outcome early during the treatment, in comparison with 18F-FDG PET/CT imaging.

Methods 48 patients with advanced gastric cancer were enrolled. Before and at the 14th day after the start of chemotherapy, whole body 18F-FLT and 18F-FDG PET/CT imaging were performed in two consecutive days. Then the patients with positive basiline 18F-FLT and 18F-FDG imaging were followed up until disease progressed or the twelfth month after treatment. SPSS for Windows (version 19.0) was used to perform data analysis.

Results 40 of the 48 patients completely accorded with the program. ΔSUVmax of both 18F-FLT and 18F-FDG was found significantly correlate with time to disease progression (TTP) (r=0.601, P<0.01 and r=0.32, P=0.044 respectively). Medium TTP was 5 months. At medium TTP, 39.2% and 20.3% for ΔSUVmax of 18F-FLT and 18F-FDG respectively were defined as the optimum cut off value for differentiation of metabolic responders and nonresponders after ROC analysis. Total predictive accuracy, sensitivity, specificity, positive and negative predictive values for 18F-FLT was 87.5% (35/40), 100% (14/14), 80.8% (21/26), 73.7% (14/19) and 100% (21/21) respectively, and for 18F-FDG was 72.5 (29/40) , 66.7% (16/24) , 81.2% (13/16), 84.2% (16/19) and 61.9% (13/21) respectively.

Conclusions 18F-FLT PET/CT imaging could be a useful way to predict therapeutic response and clinical outcome early after EOF chemotherapy in patients with advanced gastric cancer, and maybe more accurate than 18F-FDG PET/CT imaging.