Can Positron Emission Tomography/Computed Tomography with the Dual Tracers Fluorine-18 Fluoroestradiol and Fluorodeoxyglucose Predict Neoadjuvant Chemotherapy Response of Breast Cancer?-A Pilot Study

Objective: To assess the clinical value of dual tracers Positron emission tomography/computed tomography (PET/CT) F-18-fluoroestradiol (F-18-FES) and F-18-fluorodeoxyglucose (F-18-FDG) in predicting neoadjuvant chemotherapy response (NAC) of breast cancer. Methods: Eighteen consecutive patients with newly diagnosed, non-inflammatory, stage II and III breast cancer undergoing NAC were included. Before chemotherapy, they underwent both F-18-FES and F-18-FDG PET/CT scans. Surgery was performed after three to six cycles of chemotherapy. Tumor response was graded and divided into two groups: the responders and non-responders. We used the maximum standardized uptake value (SUVmax) to qualify each primary lesion. Results: Pathologic analysis revealed 10 patients were responders while the other 8 patients were non-responders. There was no statistical difference of SUVmax-FDG and tumor size between these two groups (P>0.05). On the contrary, SUVmax-FES was lower in responders (1.75+/-0.66 versus 4.42+/-1.14; U=5, P=0.002); and SUVmax-FES/FDG also showed great value in predicting outcome (0.16+/-0.06 versus 0.54+/-0.22; U=5, P=0.002). Conclusions: Our study showed F-18-FES PET/CT might be feasible to predict response of NAC. However, whether the use of dual tracers F-18-FES and F-18-FDG has complementary value should be further studied.