Regional Lymph Node Irradiation for High-risk pN0 Breast Cancer

Inclusion Criteria: Voluntarily participate and sign an informed consent form; Age\>18 years old, female； received radical surgery for breast cancer, including breast conservation surgery or mastectomy, combined with Sentinel lymph node biopsy or axillary lymph node dissection； Invasive cancer, postoperative axillary lymph node negative, with pathological staging of T1-3N0M0 stage (Stage IA, IIA, IIB)； including two or more high-risk factors based on four clinical high-risk recurrence factors \[tumor size (\>2cm), tumor site (medial and central quadrants), Ki-67 level (\>14%), and vascular status (positive)\]; KPS ≥ 80, estimated survival time \>5 years; Complete healing of Surgical incision, no incision infection, etc; Reproductive period women should undergo contraception for at least one month before study, and promise to use contraception throughout the entire study period and continue until the specified time after the end of the study Exclusion Criteria: Pregnant or lactating women; Received neoadjuvant therapy; with serious non neoplastic medical complications that affect the implementation of radiotherapy; History of malignant tumor in the past 5 years (excluding previous lobular Carcinoma in situ, skin Basal-cell carcinoma, skin Carcinoma in situ, cervical Carcinoma in situ and lung Carcinoma in situ); Simultaneous contralateral breast cancer; Previous history of neck, chest, or ipsilateral axillary radiotherapy; Active collagen vascular disease; distant metastasis confirmed by pathology or imaging;