F-18 FES PET/CT in Measuring Hormone Expression in Patients with Primary, Recurrent, or Metastatic Breast Cancer Undergoing Endocrine-Targeted Therapy

Inclusion Criteria

• Adult, non-pregnant patients with biopsy-proven or clinically obvious primary, recurrent or metastatic breast cancer
• Breast cancer from ER+ primary that is seen on other imaging tests; tumor ER expression must have been confirmed by immunohistocytochemistry of primary tumor or recurrent disease
• At least one site of disease 1.5 cm or greater is needed to meet the spatial resolution limits of PET imaging
• Patients must have been off tamoxifen or other estrogen receptor blocking agents for at least 6 weeks and off chemotherapy for 3 weeks for the initial baseline FES
• Patients must be selected for an endocrine targeted therapy regimen for treatment of their breast cancer by the referring oncologist; selected treatments may be part of experimental treatment protocols for which the patient would be separately consented
• Patients must be willing to undergo serial imaging procedures
• Patients must agree to allow access to clinical records regarding response to treatment and long term follow up

Exclusion Criteria

• An inability to lie still for the tests
• Individuals weighing more than 300 lb; (this is the weight limit of the scanner table)
• Pregnant or lactating; women of childbearing potential with either a positive or no pregnancy test at baseline are excluded
• Any other life-threatening illness (e.g. serious, uncontrolled concurrent infection or clinically significant cardiac disease – congestive heart failure, symptomatic coronary artery disease, cardiac arrhythmia not well controlled with medication)
• Use of tamoxifen, Faslodex, diethylstilbestrol (DES) or any other ER blocking agent < 6 weeks or chemotherapy < 3 weeks prior to imaging scan
• Unwillingness or inability to give informed consent
• Uncontrolled diabetes mellitus (fasting glucose > 200 mg/dL)
• Adult patients who require monitored anesthesia for PET scanning