Omission of SLNB in CN0 Early Breast Cancer

Inclusion Criteria: 1. Female patients aged 18-70 years; 2. Pathologically confirmed invasive breast cancer (regardless of pathological type) with a tumor diameter ≤ 3 cm, and planning to undergo breast surgery; 3. Negative axillary lymph nodes assessed by physical examination and imaging (2 or more of the following tests including ultrasound, breast MRI, breast PET-CT, breast PET-MRI, breast PET); 4. 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; 5. Good compliance, normal comprehension and ability to receive treatment and follow-up as required; 6. ECOG score 0-1; 7. Patients volunteered for this study and signed the informed consent form. Exclusion Criteria: 1. Bilateral/lactating/pregnant breast cancer; 2. Previous history of malignant tumor or neoplasm; 3. Clinical or imaging confirmation of distant metastasis; 4. History of previous surgery on the affected axilla; or history of surgery affecting the function of the upper extremity; 5. Prior history of radiotherapy to the breast or chest; 6. Positive pathological margins after breast-conserving surgery or mastectomy; 7. Severe coagulation disorder, or a serious systemic disease, or an uncontrollable infection; 8. Aspartate aminortransferse (AST) and Alanine aminotransferase (ALT) ≥ 1.5 times the upper limit of normal, alkaline phosphatase ≥ 2.5 times the upper limit of normal, total bilirubin ≥ 1.5 times the upper limit of normal, serum creatinine ≥ 1.5 times the upper limit of normal; left ventricular injection fraction (LVEF) \< 50% on cardiac ultrasound; 9. Inability to complete the full course of follow-up adjuvant therapy as prescribed by the doctor for various reasons; 10. No personal freedom and independent civil capacity; 11. Presence of mental disorders, addictions, etc; 12. Not eligible for enrollmentas as judged by the investigator.