Study on Using TROP2-PET and 18F-FDG PET to Predict the Efficacy of Anti TROP2 ADC Treatment in Advanced Breast Cancer

Inclusion Criteria: * Patients diagnosed with advanced/metastatic HER2-negative breast cancer with confirmed metastatic disease, regardless of being de novo diagnosed or progressed from a non-metastatic stage. * Patients who are planned to receive anti-TROP2 antibody-drug conjugate (ADC) therapy (e.g., sacituzumab govitecan or datopotamab deruxtecan) as part of routine clinical care. * Patients who will undergo protocol-defined \^68Ga-TROP2 PET/CT and \^18F-FDG PET/CT during the study (baseline imaging, with repeat imaging per protocol if applicable). * Adult patients (≥18 years) who are able to provide informed consent and comply with study procedures. Exclusion Criteria: * Patients with incomplete medical records or inability to complete the required imaging assessments. * Patients with prior exposure to an anti-TROP2 ADC. * Patients with known contraindications to PET/CT or known allergy to \^18F-FDG or the \^68Ga-TROP2 tracer (or their components). * Patients who are pregnant or breastfeeding. * Patients diagnosed with secondary primary tumors (other active malignancies), as determined by the investigator.