Androgen Receptor And Estrogen Receptor Imaging In Patients With Metastatic Breast Cancer.

11553Background: The ER, PR and HER2 expression is routinely determined in breast cancer patients for prognosis and treatment decision-making. The androgen receptor (AR) is also present in the majority of breast cancer patients, offering a potential new drug target.ER expression in tumor lesions can be visualized by 18F-fluoroestradiol (FES) PET throughout the body. The AR-expression could be visualized by 18F-fluorodihydrotestosterone (FDHT) PET in prostate cancer patients.The aim was to obtain accurate non-invasive information about ER and AR tumor receptor status with FES and FDHT PET in breast cancer patients. Methods: Metastatic breast cancer patients with an ER positive primary tumor and ≥ 1 metastasis were eligible. Patients were staged with a bone scan and chest and abdominal CT scan. Lesions visible on conventional imaging were evaluable for primary endpoint, i.e. the concordance of FES and FDHT uptake with respectively ER and AR expression determined immunohistochemically (IHC) in a metastasis. ...