The aim of this study is to explore the impact of internal mammary nodal irradiation on disease-free survival in high-risk breast cancer patients (ypN+or supra/subclavicular lymph node positive) after neoadjuvant chemotherapy.

This is a prospective, randomized phase 3 trial. Breast cancer patients with axillary lymph node-positive or supra/subclavicular lymph node metastasis underwent neoadjuvant chemotherapy were included. Patients underwent regional nodal irradiation along with breast or chest wall irradiation and randomly allocated to either IMNI or no IMNI.

Inclusion Criteria:

• Histologically confirmed invasive breast cancer
• Underwent neoadjuvant chemotherapy
• Eastern Cooperative Oncology Group Performance Status Scale 0-2
• ypN+ after neoadjuvant chemotherapy or supraclavicular/subclavicular lymph node metastasis before system therapy
• No distant metastases
• No internal mammary nodes metastases based on images before system therapy
• Willing to follow up
• Written,informed consent

Exclusion Criteria:

• Without neoadjuvant chemotherapy
• Distant metastases
• Simultaneous bilateral breast cancer
• Pathological confirmation or imaging consideration of lymph node metastasis in the internal mammary before system therapy
• Had simultaneous or previous secondary malignancies, except for non-malignant melanoma skin cancer, papillary thyroid / follicular carcinoma, cervical carcinoma in situ, contralateral non-invasive breast cancer