Can PET-Based Estradiol Challenge Test Monitor Response to Endocrine Therapy?

To reliably identify patients most likely to benefit from endocrine therapy, better methods are needed to determine the quantity and functional status of breast cancer tumor estrogen receptor (ER) and progesterone receptor (PgR). Researchers from the Alvin J. Siteman Cancer Center at the Washington University School of Medicine, St. Louis, reported a change in tumor uptake of the progestin analog 21-[18F] fluorofuranylnorprogesterone (FFNP) in subjects after a brief estradiol challenge. Their results were published in Nature Communications and suggest that tumor ER functional status may prove to be a strong predictor of benefit from endocrine therapy.