PT - JOURNAL ARTICLE AU - Michel van Kruchten AU - Erik F.J. de Vries AU - Henriette J.G. Arts AU - Neeltina M. Jager AU - Alphons H.H. Bongaerts AU - Andor W.J.M. Glaudemans AU - Harry Hollema AU - Elisabeth G.E. de Vries AU - Geke A.P. Hospers AU - Anna K.L. Reyners TI - Assessment of Estrogen Receptor Expression in Epithelial Ovarian Cancer Patients Using 16α-<sup>18</sup>F-Fluoro-17β-Estradiol PET/CT AID - 10.2967/jnumed.114.147579 DP - 2015 Jan 01 TA - Journal of Nuclear Medicine PG - 50--55 VI - 56 IP - 1 4099 - http://jnm.snmjournals.org/content/56/1/50.short 4100 - http://jnm.snmjournals.org/content/56/1/50.full SO - J Nucl Med2015 Jan 01; 56 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 &lt; 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.