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

PRIMARY OBJECTIVES:

I. Measure the effect of endocrine targeted therapy on estrogen receptor (ER) expression and
estradiol binding to the receptor using serial FES PET and fludeoxyglucose F-18 (FDG) PET.

SECONDARY OBJECTIVES:

I. Document the safety profile of FES PET in patients with breast cancer.

II. Examine associations between FES PET results and serial measurements of hormone or other
levels in peripheral blood, as related to efficacy of endocrine-targeted therapy. Correlate
FES PET uptake measures with histopathological assays and tumor microenvironment studies on
biopsy specimens, if relevant to specific treatment regimen.

OUTLINE:

Patients undergo F-18 FES PET/CT scan at baseline. Patients also undergo F-18 FES PET/CT and
FDG PET/CT between 1-12 weeks after starting therapy, and then 1-12 weeks after the second
FES PET/CT scan. Repeat FDG PET may be omitted in patients on selective estrogen receptor
degrader.

After completion of study, patients are followed up for up to 20 years.

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