Omission of ALND in Breast Cancer Patients With Axillary pCR

Inclusion Criteria: 1. Female aged between 18 and 70 years; 2. Pathologically confirmed invasive breast cancer (regardless of pathological type) with a clinical stage cT1-3; 3. Pathologically confirmed positive axillary lymph nodes with a clinical stage of N1-3; 4. Receiving a full course of neoadjuvant therapy (including neoadjuvant chemotherapy, neoadjuvant targeted therapy, neoadjuvant immunotherapy); 5. Positive axillary lymph nodes successfully stained by carbon nanoparticles injection; 6. All patients are required to undergo immunohistochemical staining for Estrogen Receptor (ER), Progesterone Receptor (PR), human epidermal growth factor receptor 2 (HER2), Ki- 67 proliferation index, and further fluorescence in situ hybridization (FISH) should be performed in HER2 2+ cases; 7. Preoperative clinical assessment (including physical examination, imaging, with or without nomogram assessment) suggests positive axillary lymph nodes converted to negative (ycN0); 8. ECOG score 0 - 1; 9. Patients voluntarily participated in this study and signed the informed consent form Exclusion Criteria: 1. Bilateral breast cancer; 2. Breast cancer during lactation period or pregnancy; 3. Physical examination or imaging examination confirmed presence of distant metastases; 4. Previous history of malignant tumor; 5. History of previous surgery on the affected axilla; or history of surgery affecting the function of the upper extremity; 6. History of radiation therapy to the breast or chest; 7. Positive incision margins for breast-conserving surgery/mastectomy; 8. Positive results of intraoperative rapid freeze pathology (including isolated tumor cells and micrometastases) for SrLNB (ypN+); 9. Those who unable to complete the full course of follow-up adjuvant therapy as prescribed for various reasons; 10. Aspartate transaminase (AST) and alanine transaminase (ALT) ≥ 1.5 times the upper limit of normal, alkaline phosphatase（ALP） ≥ 2.5 times the upper limit of normal, total bile ≥ 1.5 times the upper limit of normal, serum creatinine ≥ 1.5 times the upper limit of normal; Left Ventricular Ejection Fractions (LVEF) \< 50% in cardiac ultrasound; 11. Severe coagulation dysfunction, serious systemic disease, or uncontrolled infection; 12. Without personal freedom and independent civil capacity; 13. Those with mental disorders, addictions, who were not eligible for enrollment in the judgment of the investigator.