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) (18)F-fluoroestradiol ((18)F-FES) and (18)F-fluorodeoxyglucose ((18)F-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 (18)F-FES and (18)F-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 (18)F-FES PET/CT might be feasible to predict response of NAC. However, whether the use of dual tracers (18)F-FES and (18)F-FDG has complementary value should be further studied.