Figure 4.

Representatives images of changes in ¹⁸F‐FES uptake in the tumor during treatment. (A): Incomplete reduction of ¹⁸F‐FES uptake. A 50‐year‐old premenopausal woman with invasive ductal breast cancer, who presented with bone and lymph node metastases after 42 months of adjuvant endocrine therapy (goserelin plus aromatase inhibitor). The patient received fulvestrant therapy as first‐line endocrine therapy and had a median change in maximum standard uptake value (ΔSUVmax) of −5.1% and a progression‐free survival (PFS) of 1.8 months. This patient is shown by the first bar in Figure 3. (B): Extensive reduction of ¹⁸F‐FES uptake. A 51‐year‐old postmenopausal woman with invasive ductal breast cancer, who presented with lung and bone metastases after a 7‐year disease‐free interval (completed 5 years of adjuvant tamoxifen therapy). The patient received fulvestrant therapy as first‐line endocrine therapy and had a median ΔSUVmax of 73.2% and a PFS of 11.7+ months. The patient's best response was stable disease. This patient is shown by the 29th bar in Figure 3.Abbreviation: FES, fluoroestradiol.