TABLE 3

Studies with ¹⁸F-FES PET in Breast Cancer Patients

No. of patients	Study aim(s)	Results	Reference
47	Quantify tumor ¹⁸F-FES uptake as predictor of endocrine therapy response	Absence of uptake predicted failure of endocrine therapy	38
19	Investigate utility of ¹⁸F-FES PET for predicting overall response to first-line endocrine therapy in MBC	Low or absent ¹⁸F-FES uptake correlated with lack of ER expression	39
11	Assess serial ¹⁸F-FES PET and ¹⁸F-FDG PET for predicting response to tamoxifen	Increase in ¹⁸F-FDG uptake and decrease in ¹⁸F-FES uptake after start of tamoxifen predicted response	40
30	Measure changes in ¹⁸F-FES uptake with aromatase inhibitors, tamoxifen, or fulvestrant	No effect with aromatase inhibitors; ∼55% decrease with tamoxifen or fulvestrant	41
40	Assess serial ¹⁸F-FES PET and ¹⁸F-FDG PET for predicting response to tamoxifen	Increase in ¹⁸F-FDG uptake and decrease in ¹⁸F-FES uptake after start of tamoxifen predicted response	42
16	Evaluate whether 500 mg of fulvestrant optimally abolishes ER availability in tumor	¹⁸F-FES PET showed residual ER availability during fulvestrant therapy in 38% of patients; this finding was associated with early progression	43
59	Investigate whether ¹⁸F-FES PET and serial ¹⁸F-FDG PET predict response to endocrine therapy	Baseline ¹⁸F-FES uptake and metabolic flare after estradiol challenge predicted treatment response	68
17	Assess correlation between ¹⁸F-FES uptake and IHC	Good correlation for ER was observed	69
53	Compare ¹⁸F-FES PET with ¹⁸F-FDG PET and IHC	¹⁸F-FES PET showed 88% agreement with IHC and provided information not obtained with ¹⁸F-FDG PET	70
91	Measure variability in ¹⁸F-FES uptake between and within patients	Substantial variations in ¹⁸F-FES uptake between and within patients were observed	71
13	Assess feasibility of ¹⁸F-FES PET for detecting primary ER-positive breast cancer lesions and correlation with in vitro status	Focal uptake of ¹⁸F-FES was seen in all tumors; uptake correlated well with in vitro assays	72
239	Assess correlation between ¹⁸F-FES PET and clinical and laboratory data, effects of previous treatments, and ¹⁸F-FES metabolism	¹⁸F-FES uptake correlated positively with BMI and inversely with plasma sex hormone–binding globulin levels and binding capacity	73
18	Assess clinical value of dual PET/CT tracers ¹⁸F-FES and ¹⁸F-FDG in predicting response to NAC	¹⁸F-FES PET/CT may be feasible for predicting response to NAC	74
32	Investigate heterogeneity of ER expression among tumor sites with ¹⁸F-FES PET	¹⁸F-FES uptake and ¹⁸F-FDG uptake varied greatly within and among patients; ¹⁸F-FES PET/CT showed heterogeneous ER expression	75
48	Correlate ¹⁸F-FES PET with ER expression in patients with primary, operable breast cancer	¹⁸F-FES PET SUV correlated with IHC ER expression; size of primary tumor was associated with ¹⁸F-FES PET SUV	76
33	Evaluate clinical value of ¹⁸F-FES PET/CT in assisting with individualized treatment decisions for ER-positive breast cancer patients	Treatment plan was changed in 48.5% of cases on basis of ¹⁸F-FES PET/CT results	53

ICH = immunohistochemistry; BMI=body mass index; NAC = neoadjuvant chemotherapy.