PET Imaging of Estrogen Receptors as a Diagnostic Tool for Breast Cancer Patients Presenting with a Clinical Dilemma

Abstract

16a-18 F-fluoro-17b-estradiol ( 18 F-FES) is an estrogen receptor (ER)-specific PET tracer with various potential interesting applications. The precise contribution of this technique in current clinical practice, however, has yet to be determined. Therefore, the aim of this study was to evaluate the value of 18 F-FES PET in breast cancer patients presenting with a clinical dilemma. Methods: 18 F-FES PET examination could be requested by referring physicians for patients with a history of ER-positive breast cancer and the presence of a clinical dilemma despite complete standard work-up. All requests for 18 F-FES PET required a positive arbitration by a dedicated medical oncologist and nuclear medicine physician. The referring physician was asked to fill in validated questionnaires before, shortly after, and at more than 3 mo after 18 F-FES PET to determine indication, diagnostic value, and therapeutic consequences of 18 F-FES PET. To further validate 18 F-FES PET findings, 18 F-FES PET lesions were quantified and compared with centrally reviewed conventional imaging. Results: Thirty-three patients underwent 18 F-FES PET between December 2008 and October 2010. 18 F-FES PET was requested to evaluate equivocal lesions on conventional work-up (n 5 21), ER status in metastatic patients (n 5 10), and the origin of metastases (n 5 2). 18 F-FES-positive lesions were observed in 22 patients. 18 F-FES PET was especially sensitive for bone metastases, detecting 341 bone lesions, compared with 246 by conventional imaging. The sensitivity for liver metastases was poor, and quantification of 18 F-FES uptake in liver lesions was hampered by high physiologic background. 18 F-FES uptake was highly variable between all metastases (range of standardized uptake value, 1.20-18.81), and 45% of the patients with a positive 18 F-FES PET finding had both 18 F-FES-positive and 18 F-FES-negative metastases. 18 F-FES PET improved diagnostic understanding in 88% of the patients and led to therapy change in 48% of the patients. Conclusion: With the exception of liver metastases, whole-body imaging of ER expression with 18 F-FES PET can be a valuable additional diagnostic tool when standard work-up is inconclusive. 18 F-FES PET supported therapy decisions by improving diagnostic understanding and providing information on ER status of tumor lesions.

Measuring Residual Estrogen Receptor Availability during Fulvestrant Therapy in Patients with Metastatic Breast Cancer

“…In our study, as in other FES-PET studies, patients were required to discontinue tamoxifen at least 5 weeks before baseline FES-PET to prevent competitive binding ( 14 ). However, the lowest median FES uptake was recorded in the 4 patients who used tamoxifen until 5 weeks before FES-PET.…”

“…All 4 patients who withdrew from tamoxifen treatment shortly (5-6 weeks) before baseline FES-PET/CT had lower FES uptake when compared with patients who did not recently use tamoxifen (median SUV max , 1.7 vs 4.1; P = 0.004). Coincidentally, an earlier FES-PET that was performed during treatment with an aromatase inhibitor was available for 2 of these 4 patients ( 14 ).…”

“…Exclusion criteria were previous fulvestrant therapy, the presence of life-threatening visceral metastases, central nervous system metastases, and more than two lines of palliative chemotherapy. To prevent competition between FES and drugs from previous therapies, the patients were required to discontinue drugs known to bind ER for at least 5 weeks before baseline PET imaging ( 14 ).…”

[18F]-Estradiol PET/CT Imaging in Breast Cancer Patients

“…The physiological uptake in the liver is due to metabolization exceeding the uptake as shown in most ER-positive metastases [15]. We did observe focal 'cold' lesions in one patient.…”

Assessment of Estrogen Receptor Expression in Epithelial Ovarian Cancer Patients Using 16α-18F-Fluoro-17β-Estradiol PET/CT

“…First, we showed that 18 F-FES uptake was absent in the cystic parts of lesions and therefore a sufficiently large (e.g., .10 mm) solid component is required for quantification of tumor 18 F-FES uptake. Second, in contrast to breast cancer, for which 18 F-FES-positive lesions can usually readily be observed also without a concurrent CT scan (23), in this study, ovarian cancer lesions had to be allocated using a concurrent or recent contrast-enhanced diagnostic CT scan. This limitation is because most lesions develop in the abdominal cavity, in which visualization is hampered by high physiologic background tracer levels in the liver, gallbladder, intestines, uterus, kidneys, and bladder (24).…”