Adjuvant Regional Nodal Radiation Therapy for One Week in Breast Cancer

Eligible breast cancer patients will receive super hypofractionated radiotherapy of 5.2 Gy in 5 fractions within one week and a sequential tumor bed boost of 5.2 Gy in 2 fractions to the conserved breast. The dose is prescribed to ipsilateral chest wall or whole breast and regional lymph regions (including supraclavicular/infraclavicular region, internal mammary nodes, and any part of the axillary bed at risk). All patients are treated with intensity modulated radiation therapy (IMRT) technique or intensity modulated proton therapy (IMPT). The primary endpoint is ≥2 grade any acute radiation induced toxicity event. Patients will be followed for at least 5 years to evaluate the acute and late radiation-induced toxicity, locoregional recurrence, over survival, distant metastasis, and quality of life. Calculation of the required number of cases based on an alpha of 0.05 and a power of 80% with a maximal tolerable toxicity difference of 10% during and within 6 months after RNI comparing to conventional radiotherapy and lost rate of follow up of 10%. In total 197 patients are needed to be recruited.