Postmastecomy Internal Mammary Nodal Irradiation for High-risk Breast Cancer Patients

Eligible patients are randomized into 2 groups: chest wall/whole breast and supraclavicular nodal +-axillary plus internal mammary nodal irradiation, and chest wall/whole breast and supraclavicular nodal +-axillary nodal irradiation. The prescription dose is 50 Gy in 25 fractions over 5 weeks or 43.5Gy in 15 fractions over 3 weeks. Breast cancer patients treated with breast-conserving surgery will receive tumor bed boost.

During and after radiotherapy, the patients are followed and the efficacy and toxicities of radiotherapy are evaluated.

Inclusion criteria

• Eastern Cooperative Oncology Group Performance Status Scale 0-2
• Histologically confirmed invasive breast cancer
• Underwent total mastectomy/breast-conserving surgery and axillary dissection(10 or more axillary lymph nodes detected) and negative margins
• Patients who had ≥4 positive axillary lymph nodes; or 1-3positive axillary lymph nodes and T3-4; or 1-3positive axillary lymph nodes and T1-2, and score≥3 based on the following high risk factors: age≤40 years(score 1), primary tumor in the inner quadrant (score 1), 2-3 positive axillary lymph nodes (score 1), positive vascular invasion (score 1), re-staged based on eighth Cancer Staging System staging system(IB-IIA score 1， IIB-IIIA score 2); or ypN+ after neoadjuvant chemotherapy
• No supraclavicular or internal mammary nodes metastases based on images before system therapy
• No distant metastases
• Could tolerate radiotherapy
• Treated with chemotherapy (anthracycline and/or taxane-based combined chemotherapy, ≥6 cycles)
• Anticipated to receive endocrine therapy for 5 years if indicated
• Anticipated to receive anti-HER2 therapy for 1 years if indicated
• LVEF≥50% based on echocardiogram
• Willing to follow up
• Written,informed consent

Exclusion criteria

• Simultaneous bilateral breast cancer
• Sentinel lymph node biopsy only without axillary dissection
• Had received internal mammary node dissection
• No imaging assessment of the internal mammary nodal before system therapy
• One-stage breast reconstruction
• Severe cardiac insufficiency; myocardial infarction or uncorrected unstable arrhythmia or uncorrected unstable angina in the last 3 months; pericardial disease
• Had history of chest wall or supraclavicular radiotherapy
• 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