Clinical Potential of Estrogen and Progesterone Receptor Imaging.

Molecular imaging using 16α-[18 F]fluoro-17β-estradiol (FES) and 18 F-fluoro-furanyl-norprogesterone PET can assess in vivo function of steroid hormone receptors in breast cancer. These experimental agents have been tested in many single-center clinical trials and show promise to elucidate prognosis and predict endocrine therapy response. The current multicenter trial of FES-PET imaging will help bring this radiotracer closer to clinical use. There is tremendous potential for these tracers to advance drug development, enhance understanding of estrogen receptor-positive tumor biology, and personalize treatment.