A Phase Ⅲ Randomized Clinical Trial of Postmastectomy Hypofractionation Radiotherapy in High-risk Breast Cancer

Inclusion Criteria: * Ipsilateral histologically confirmed invasive breast cancer * Undergone total mastectomy and axillary dissection * T3-4,or \>=4 positive axillary lymph nodes * Fit for chemotherapy(if indicated),endocrine therapy(if indicated)and postoperative irradiation * Written,informed consent * cT3-4,or cN2, or pathological positive axillary lymph nodes during mastectomy for patients who had received neoadjuvant chemotherapy or hormone therapy * no supraclavicular or internal mammary nodes metastases * no distant metastases * enrollment date no more than 8 months after surgery or no more than 2 months after chemotherapy for patients who didn't receive neoadjuvant systemic therapy. * enrollment date no more than 2 months after surgery for patients who had received neoadjuvant systemic therapy and didn't need adjuvant chemotherapy. Exclusion Criteria: * Patients who undergone previous irradiation to the ipsilateral chest wall and supraclavicular region * Previous or concurrent malignant other than non-melanomatous skin cancer * Unable or unwilling to give informed consent * bilateral breast cancer * immediate or delayed ipsilateral breast cancer reconstruction