Assessment of estrogen receptor expression in epithelial ovarian cancer patients using 16α-18F-fluoro-17β-estradiol PET/CT

The estrogen receptor a (ER alpha) is expressed in approximately 70% of ovarian cancer tumors. PET of tumor ER alpha expression with the tracer 16 alpha-F-18-fluoro-17 beta-estradiol (F-18-FES) may be valuable to select ovarian cancer patients for endocrine therapy. The aim of this study was to evaluate the feasibility of F-18-FES PET to determine tumor ERa expression noninvasively in epithelial ovarian cancer patients. Methods: F-18-FES PET/CT was performed shortly before cytoreductive surgery. Tumor F-18-FES uptake was quantified for all lesions 10 mm or greater on CT and expressed as maximum standardized uptake value. F-18-FES PET/CT findings were compared with histology and immunohistochemistry for ER alpha, ER beta, and progesterone receptor. Receptor expression was scored semiquantitatively using H-scores (percentage of positive tumor cells Chi 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 F-18-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 F-18-FES uptake correlated with the semiquantitative immunoscore for ER alpha (rho = 0.65, P