89Zr-Trastuzumab PET/CT for Detection of Human Epidermal Growth Factor Receptor 2–Positive Metastases in Patients With Human Epidermal Growth Factor Receptor 2–Negative Primary Breast Cancer

Purpose The aim of this study was to determine if imaging with 89 Zr-trastuzumab, a human epidermal growth factor receptor 2 (HER2)–targeting PET tracer, can detect HER2-positive metastases in patients with HER2-negative primary breast cancer. Methods As part of an institutional review board–approved, prospective clinical trial of 89 Zr-trastuzumab PET/CT (ClinicalTrials.gov identifier NCT02286843), a second group of 11 patients with...