Clinical Application of ctDNA Dynamic Monitoring in Neoadjuvant Therapy for HER2-positive Breast Cancer Patients

This study uses blood tests that detect circulating tumor DNA (cancer DNA shed into the bloodstream) to monitor how well neoadjuvant therapy (treatment given before surgery) is working in women with HER2-positive breast cancer — a subtype of breast cancer that responds to specific targeted drugs. **You may be eligible if...** - You are a woman between 18 and 75 years old - You have confirmed HER2-positive breast cancer (tumour larger than 2 cm) confirmed by biopsy - You have not received any prior breast cancer treatment - You are planning to undergo neoadjuvant (pre-surgery) chemotherapy - Your performance status is adequate (ECOG 0–1) **You may NOT be eligible if...** - Your cancer has already spread (stage IV/metastatic) - You have another active cancer - You have already started breast cancer treatment Talk to your doctor to see if this trial is right for you.