No Axillary Surgical Treatment in Clinically Lymph Node Negative Patients on Ultrasonography After Neoadjuvant Chemotherapy

This study is testing whether women with breast cancer can safely skip lymph node surgery under the armpit after completing chemotherapy before surgery (called neoadjuvant chemotherapy), when ultrasound shows the lymph nodes look clear. **You may be eligible if...** - You are a woman aged 19 or older - You have been diagnosed with invasive breast cancer confirmed by biopsy - Your cancer was staged as early-to-locally advanced (T1-T3, no distant spread) before chemotherapy - If your lymph nodes were initially involved, you have HER2-positive or triple-negative breast cancer, and your tumor shrank by at least 30% on MRI after chemotherapy - Your lymph nodes look clear on ultrasound after chemotherapy - You are planning breast-conserving surgery (lumpectomy) and have completed at least half of your chemotherapy - You are in reasonably good physical condition (ECOG 0-2) **You may NOT be eligible if...** - You have had any other cancer in the past 5 years - You have cancer in both breasts - You need a full mastectomy - Your tumor is still larger than 5 cm after chemotherapy - You are male, pregnant, or breastfeeding Talk to your doctor to see if this trial is right for you.