[18F]FES PET/CT for the Detection of Distant Metastasis in Low-grade ER-positive Stage III Breast Cancer

This study uses a special type of PET/CT scan with a tracer called [18F]FES — which targets oestrogen receptors — to detect distant spread (metastasis) of a specific type of breast cancer: hormone receptor-positive, low-grade, Stage III breast cancer. The goal is to find out if this scan is more accurate than standard imaging for this cancer type. **You may be eligible if...** - You are 19 or older - You have been newly diagnosed with invasive breast cancer within the past 90 days - Your cancer is oestrogen receptor-positive and low-grade (Grade 1 or 2) - Your cancer is Stage IIIA, IIIB, or IIIC - You have undergone or are scheduled to undergo standard staging scans (CT of chest/abdomen/pelvis and bone scan) **You may NOT be eligible if...** - Your breast cancer is not oestrogen receptor-positive or not low-grade - Your cancer is Stage I, II, or IV - You have not completed required standard staging scans Talk to your doctor to see if this trial is right for you.