F-18 16 Alpha-Fluoroestradiol-Labeled Positron Emission Tomography in Predicting Response to First-Line Hormone Therapy in Patients With Stage IV Breast Cancer

PRIMARY OBJECTIVES: I. Estimate the ability of \[\^18F\] FES positron emission tomography (PET) or PET/computed tomography (CT) uptake at the level of standard uptake value (SUV) \< 1.5 to predict overall response (OR) to first line endocrine therapy for metastatic breast cancer. SECONDARY OBJECTIVES: I. Evaluate the independent role of \[\^18F\] FES in predicting response and time to progression in patients treated with first-line endocrine therapy for metastatic breast cancer. II. Examine the role of \[\^18F\] FES in predicting OR or clinical benefit (CB), in concert with tissue assay of levels of estrogen receptor (ER) messenger ribonucleic acid (mRNA) measured using quantitative polymerase chain reaction (PCR), and semi-quantitative interpretation of estrogen receptor (ER), progesterone receptor (PgR), androgen receptor (AR), and human epidermal growth factor-2 (HER2), in addition to serial measures of hormone levels in plasma. III. Evaluate the relationships among \[\^18F\] FES, semi-quantitative ER from immunohistochemistry (IHC), and ER mRNA as measured by quantitative PCR. IV. Document the safety profile of \[\^18F\] FES PET in newly diagnosed patients with metastatic breast cancer. V. Evaluate FES SUV \< 1.5 as the optimal cutpoint for predicting OR to first-line endocrine therapy for metastatic breast cancer. VI. Estimate the rate of \[\^18F\] FES SUV \< 1.5 in newly diagnosed metastatic breast cancer patients planning a course of endocrine therapy. OUTLINE: Patients undergo \[\^18F\] FES PET scan. Patients also undergo standard clinical fludeoxyglucose F 18 (FDG)-PET or FDG-PET/CT scan up to 14 days prior to \[\^18F\] FES PET scan. After completion of study treatment, patients are followed up for at least 6 months.