Magseed Enabled Long-Term Localization of Axillary Lymph Nodes

This study is testing whether a tiny magnetic seed (called Magseed) can be placed into a lymph node in the armpit before chemotherapy in breast cancer patients, allowing surgeons to accurately find and remove the exact lymph node months later after treatment is complete. This technique may allow for less extensive surgery. **You may be eligible if...** - You are 18 years or older - You have breast cancer with confirmed spread to an armpit lymph node (verified by needle biopsy) - A small metal clip has been placed in that lymph node before you start chemotherapy - You are planned to receive chemotherapy before surgery (neoadjuvant chemotherapy) - You are a candidate for targeted axillary surgery (removing fewer lymph nodes) **You may NOT be eligible if...** - Your lymph node involvement has not been confirmed by biopsy - You are not receiving chemotherapy before surgery - You have conditions that prevent safe use of the magnetic seed Talk to your doctor to see if this trial is right for you.