Using FDG-PET/CT to Assess Response of Bone-Dominant Metastatic Breast Cancer, FEATURE Study

Inclusion Criteria

• Patient must be >= 18 years of age on the day of signing informed consent
• Patient must have an Eastern Cooperative Oncology Group (ECOG) performance (performance status [PS]) =< 2
• Patient must have radiographically confirmed metastatic breast cancer with histologic confirmation of either metastatic or primary tumor biopsy by local assessment that is hormone receptor positive by American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines and with known HER2 status. * NOTE: Confirmation can be documented via a report from a metastatic biopsy; a separate biopsy does not need to be completed. If there is no report from a metastatic biopsy, the pathology report from primary breast cancer diagnosis documenting breast cancer along with estrogen receptor (ER), progesterone receptor (PR) and HER2 status can be utilized
• Patient must have radiologically confirmed bone-dominant (BD) or bone-only (BO) disease confirmed by scans obtained within 60 days prior to registration * BD is defined as disease involving bone with or without limited measurable metastases by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, with >= 1 non-irradiated bone metastasis on imaging ** NOTE: Limited measurable metastases include lymph nodes and the soft tissue components of lytic or mixed lytic/blastic bone metastases. Any number of lymph nodes =< 3 cm and up to 2 lymph nodes > 3 cm will be allowed. Up to 5 measurable soft tissue components of lytic or mixed lytic/blastic bone metastases will be allowed. Sites of radiation to bone lesions prior to enrollment must be recorded * BO is defined as detectable disease confined within the bone (any site, any number of lesions). Diagnosis requires abnormalities identified by imaging (bone scan or CT or PET/CT or magnetic resonance imaging [MRI]) with no other sites of metastases identified and with >= 1 non-irradiated bone metastasis on imaging
• Patient must have no contraindication to FDG-PET imaging which includes glucose values > 200 mg/dL and severe claustrophobia
• Patient must be newly starting one of the following systemic therapies: * Plan to receive either 1st, 2nd or 3rd line endocrine therapy for metastatic breast cancer. Endocrine therapy may include selective estrogen receptor modulators (SERMs), aromatase inhibitors, and/or fulvestrant that may be combined with Food and Drug Administration (FDA)-approved biologic agents(examples include CDK 4/6 inhibitors mTOR inhibitors and PARP inhibitors for gBRCA mutation) * Plan to receive chemotherapy or antibody drug conjugates per National Comprehensive Cancer Network (NCCN) or institutional standard * Plan to receive HER2-targeted therapy per ASCO, NCCN, and/or institutional guidelines as indicated for patients with HER2 positive disease * NOTE: The use of bone-stabilizing agents (bisphosphonates or denosumab) is permitted * NOTE: Dose modification of an existing treatment does not qualify as a new therapy
• Patient must meet institutional guidelines for renal function for MRI and CT scanning
• Patient must have life expectancy estimated at >= 24 weeks
• Patient must be participating in the trial at an institution which has agreed to perform the imaging research studies, completed the ECOG-American College of Radiology Imaging Network (ACRIN) defined PET/CT scanner qualification procedures and received ECOG-ACRIN PET/CT scanner approval
• Patient must complete the baseline (T0) FDG-PET within 28 days after registration. A FDG-PET/CT completed prior to registration may be used if all imaging parameters have been met and patient is able to start treatment within 21 days after completion of FDG/PET CT * For patients completing the baseline (T0) FDG-PET AFTER registration all parameters must be met * For patients who completed the baseline (T0) FDG-PET PRIOR to registration all parameters must be met with the following exemption: ** Pregnancy testing documentation prior to FDG-PET (T0 time point) for patients of childbearing potential will not be required

Exclusion Criteria

• Patients with RECIST 1.1 measurable lesions in viscera, active central nervous system (CNS), leptomeningeal carcinomatous or pleural or peritoneal disease will not be eligible. Patients with prior CNS metastases treated with radiation or resection and without evidence of clinical or radiographic progression within 28 days of registration are eligible
• Patient must not have received colony stimulating growth factor within 14 days prior to completing the T0 FDG-PET/CT scan
• Patients who have received greater than 3 lines of cytotoxic chemotherapy for metastatic breast cancer are not eligible
• Patients using an investigational agent or using an investigational device within 3 weeks of T0 FDG PET/CT are not eligible
• Patients with known additional malignancy that is progressing or requires active treatment are not eligible. Exceptions include basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or in situ cervical cancer that has undergone potentially curative therapy
• Patient must not be pregnant because FDG is a radiopharmaceutical with the potential for teratogenic effects and PET/CT involves additional radiation exposure. In addition, because of radiation exposure to a nursing infant from FDG, patients who are breastfeeding are also excluded from this study. All patients of childbearing potential must have a blood test or urine study must be done within 7 days prior to FDG-PET/CT to rule out pregnancy