Steroid receptor ligands for breast cancer targeting: an insight into their potential role as PET imaging agents.

The design and development of radiolabelled steroid derivatives has been an important area of research due to their wellknown value in breast cancer targeting. The estrogen receptor (ER) and progesterone receptor (PR) are important biomarkers in the diagnosis, prognosis and follow-up of the therapeutic response of breast tumours. Thus, several radioligands based on estrogens and progestins have been proposed for targeted functional ER imaging. The aim of this review is to survey and analyze the developments in this field, which have led to the design of a number of PET steroid-based imaging agents, a few of which seem to be promising as radiopharmaceuticals for detection of ER-positive breast tumours.