RT Journal Article SR Electronic T1 Assessment of Estrogen Receptor Expression in Epithelial Ovarian Cancer Patients Using 16α-18F-Fluoro-17β-Estradiol PET/CT JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 50 OP 55 DO 10.2967/jnumed.114.147579 VO 56 IS 1 A1 Michel van Kruchten A1 Erik F.J. de Vries A1 Henriette J.G. Arts A1 Neeltina M. Jager A1 Alphons H.H. Bongaerts A1 Andor W.J.M. Glaudemans A1 Harry Hollema A1 Elisabeth G.E. de Vries A1 Geke A.P. Hospers A1 Anna K.L. Reyners YR 2015 UL http://jnm.snmjournals.org/content/56/1/50.abstract AB The estrogen receptor α (ERα) is expressed in approximately 70% of ovarian cancer tumors. PET of tumor ERα expression with the tracer 16α-18F-fluoro-17β-estradiol (18F-FES) may be valuable to select ovarian cancer patients for endocrine therapy. The aim of this study was to evaluate the feasibility of 18F-FES PET to determine tumor ERα expression noninvasively in epithelial ovarian cancer patients. Methods: 18F-FES PET/CT was performed shortly before cytoreductive surgery. Tumor 18F-FES uptake was quantified for all lesions 10 mm or greater on CT and expressed as maximum standardized uptake value. 18F-FES PET/CT findings were compared with histology and immunohistochemistry for ERα, ERβ, and progesterone receptor. Receptor expression was scored semiquantitatively using H-scores (percentage of positive tumor cells × staining intensity). The optimum threshold to discriminate ER-positive and -negative lesions was determined by receiver-operating-characteristic analysis. Results: In the 15 included patients with suspected ovarian cancer, 32 measurable lesions greater than 10 mm were present on CT. Tumor 18F-FES uptake could be quantified for 28 lesions (88%), and 4 lesions were visible but nonquantifiable because of high uptake in adjacent tissue. During surgery, histology was obtained of 23 of 28 quantified lesions (82%). Quantitative 18F-FES uptake correlated with the semiquantitative immunoscore for ERα (ρ = 0.65, P < 0.01) and weakly with progesterone receptor expression (ρ = 0.46, P = 0.03) and was not associated with ERβ expression (ρ = 0.21, P = 0.33). The optimum threshold to discriminate ERα-positive and ERα-negative lesions was a maximum standardized uptake value greater than 1.8, which provided a 79% sensitivity, 100% specificity, and area under the curve of 0.86 (95% confidence interval, 0.70–1.00). In 2 of 7 patients with cytology/histology available at primary diagnosis and at debulking surgery, immunohistochemical ERα expression had changed over time. 18F-FES PET was in accordance with histology at debulking surgery but not at primary diagnosis, indicating that 18F-FES PET could provide reliable information about current tumor ERα status. Conclusion: 18F-FES PET/CT can reliably assess ERα status in epithelial ovarian cancer tumors and metastases noninvasively. Evaluation of the predictive value of 18F-FES PET/CT for endocrine therapy in epithelial ovarian cancer patients is warranted.