Dr. Jennifer Specht of the University of Washington and Fred Hutch Cancer Center in Seattle presented the results of the ECOG-ACRIN FEATURE study at the Breast Cancer Symposium in San Antonio. This is a phase II study evaluating fluorodeoxyglucose (FDG)-PET/CT in monitoring response to treatment in patients with metastatic breast cancer, particularly bone dominant breast cancer. The study tests FDG-PET/CT as a binary predictor of progression-free survival (PFS) using modified PERCIST criteria. Patients receive FDG intravenously and undergo a PET/CT scan at baseline (within 21 days prior to standard systemic therapy) and after 12 weeks. The study is also evaluating the ability of FDG-PET/CT to detect new lesions not picked up by standard CT or bone scans. In addition, it is examining changes in circulating tumor DNA (ctDNA) to predict PFS, time to bone complications, and overall survival. Patients are excluded if they are pregnant or breastfeeding due to radiation risk. The study continues to follow patients for up to 3 years after enrollment[1].