Assessment of Estrogen Receptor Expression in Epithelial Ovarian Cancer Patients Using 16a-18F-Fluoro-17b-

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 stan-dardized uptake value. 18F-FES PET/CT findings were compared with histology and immunohistochemistry for ERα, ERβ, and pro-gesterone receptor. Receptor expression was scored semiquanti-tatively 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 ovar