Tumour Localisation With Magnetic Clip Before Neoadjuvant Chemotherapy.

This study evaluates using a magnetic clip (Magseed) to mark a breast tumor before starting chemotherapy, so surgeons can precisely locate and remove the correct tissue during surgery after chemotherapy has potentially shrunk or shifted the tumor. **You may be eligible if...** - You are 18 or older and planned for chemotherapy before breast cancer surgery - You are scheduled for breast-conserving surgery with targeted axillary dissection or sentinel lymph node biopsy using magnetic technique - You have signed informed consent before the procedure **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have an iron overload condition - You have a known allergy to iron or dextran compounds - You are unable to understand the study information or give consent - You are planned to have an MRI scan to check tumor response during chemotherapy (the clip may interfere) Talk to your doctor to see if this trial is right for you.