Study of Dotatate Imaging in Breast Cancer

Inclusion Criteria: Age of at least 18 years at the time of signing the informed consent. Biopsy proven, ER+, HER2 any, clinically progressive, Stage IV breast cancer requiring restaging. For women of childbearing potential (WOCBP): a. Negative serum pregnancy test within 48 hours of Ga-68-DOTATATE injection. A women is considered to be of childbearing potential if she is post-menarchal, has not reached postmenopausal state (≥ 12 continuous months of amenorrhea [no menstrual bleeding of any kind, including menstrual period, irregular bleeding, spotting, etc.] with no identified cause other than menopause), and has not undergone surgical sterilization (total hysterectomy, or bilateral tubal ligation or bilateral oophorectomy at least 6 weeks before taking study drug). Willingness and ability to provide written informed consent prior to any study-specific assessments and procedures commence. Exclusion Criteria: Known hypersensitivity to Gallium-68 DOTATATE or Copper-64 DOTATATE, octreotate, or any of the excipients of Gallium-68 DOTATATE or Copper-64 DOTATATE Current high-dose glucocorticoid (≥ 20 mg prednisone daily or equivalent); long acting SSA within the last 28 days; short acting SSA that cannot be interrupted for 24 hours. Unable to perform PET/CT scans according to technical specifications and local guidelines. Concurrent primary malignancy, except adequately treated carcinoma in situ, non-melanoma carcinoma of the skin or any other curatively treated malignancy that has achieved complete response and is not expected to require treatment for recurrence during participation in the study. Current somatic or psychiatric disease/condition that may interfere with the objectives and assessments of the study. Unable or unwilling to comply with the requirements of the study protocol. Prior participation in any interventional clinical study within 30 days prior to SSTR PET/CT scan.