Clinical Research Directory

Inclusion Criteria: 1. Female patients pathologically confirmed with primary invasive breast cancer via core needle biopsy; 2. Aged 18 years or older; 3. No enlarged lymph nodes palpable in the axilla on clinical examination; ultrasound reveals 1 or 2 abnormal ipsilateral axillary lymph nodes with malignant features (cortical thickening \>3 mm, hypoechoic, etc.), and at least one of them is confirmed metastatic by biopsy; 4. Maximum diameter of breast tumor ≤5 cm (cT1-2); 5. No distant metastasis detected on tumor staging examinations; 6. No prior neoadjuvant therapy received; 7. Sentinel lymph node biopsy combined with wire-localized lymph node biopsy completed by attending physicians per routine clinical practice; 8. Patients meet one of the following criteria for combined lymph node biopsy results and surgical management: total number of positive lymph nodes is 1-2 with breast-conserving surgery and omission of axillary lymph node dissection; or total number of positive lymph nodes is 1-2 with modified radical mastectomy; or total number of positive lymph nodes exceeds 2, with axillary lymph node dissection performed regardless of breast-conserving surgery or total mastectomy; 9. Voluntarily participating in this observational study and signing an informed consent form. Exclusion Criteria: 1. Bilateral breast cancer; 2. Stage IV breast cancer; 3. Receipt of neoadjuvant therapy prior to surgery; 4. Previous ipsilateral axillary surgery history (e.g., osmidrosis surgery, lymph node biopsy) and history of axillary radiotherapy; 5. Coexistence of other malignant tumors within the past 5 years, excluding cured cutaneous squamous cell carcinoma, basal cell carcinoma, non-muscle invasive bladder cancer, cervical carcinoma in situ, breast carcinoma in situ, etc.; 6. Pregnant or lactating women; 7. Severe cardiac and pulmonary insufficiency precluding surgical tolerance.