Omission of ALND in Breast Cancer Patients With Axillary pCR

Inclusion Criteria: Female aged between 18 and 70 years; Pathologically confirmed invasive breast cancer (regardless of pathological type) with a clinical stage cT1-3; Pathologically confirmed positive axillary lymph nodes with a clinical stage of N1-3; Receiving a full course of neoadjuvant therapy (including neoadjuvant chemotherapy, neoadjuvant targeted therapy, neoadjuvant immunotherapy); Positive axillary lymph nodes successfully stained by carbon nanoparticles injection with/without titanium clip marking; 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; Preoperative clinical assessment (including physical examination, imaging, with or without nomogram assessment) suggests positive axillary lymph nodes converted to negative (ycN0); ECOG score 0 - 1; Patients voluntarily participated in this study and signed the informed consent form Exclusion Criteria: Bilateral breast cancer; Breast cancer during lactation period or pregnancy; Physical examination or imaging examination confirmed presence of distant metastases; Previous history of malignant tumor; History of previous surgery on the affected axilla; or history of surgery affecting the function of the upper extremity; History of radiation therapy to the breast or chest; Positive incision margins for breast-conserving surgery/mastectomy; Positive results of intraoperative rapid freeze pathology (including isolated tumor cells and micrometastases) for SrLNB (ypN+); Those who unable to complete the full course of follow-up adjuvant therapy as prescribed for various reasons; 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; Severe coagulation dysfunction, serious systemic disease, or uncontrolled infection; Without personal freedom and independent civil capacity; Those with mental disorders, addictions, who were not eligible for enrollment in the judgment of the investigator.