Magnetic Marker Localization for Occult Breast Cancer and Target Axillary Dissection in Node-positive Breast Cancer Post-neoadjuvant Chemotherapy

This study is testing the use of a tiny magnetic marker (instead of wire localization) to precisely locate and surgically remove breast cancer tumors and lymph nodes that cannot be felt by hand after chemotherapy treatment before surgery. **You may be eligible if:** - You have invasive breast cancer in the breast and 1–3 nearby lymph nodes (cT1-3N1 staging) - You are planned to receive chemotherapy before surgery (neoadjuvant chemotherapy) - You are mentally able to give informed consent - You are interested in breast-conserving surgery and targeted lymph node removal **You may NOT be eligible if:** - Your cancer has spread to distant organs, involves multiple areas of the breast, or is inflammatory breast cancer - You have had previous surgery or radiation to the same armpit - You have an allergy to dextran or iron compounds - You have an iron storage disorder - You are pregnant or breastfeeding - You have a pacemaker or metal implants in your chest or shoulder Talk to your doctor to see if this trial is right for you.