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.