The role of postoperative regional nodal irradiation (RNI) for T1-2N1 intermediate-risk breast cancer is controversial, and there is a lack of class I evidence of a survival benefit from RNI. A number of retrospective studies of breast cancer patient been undertaken to risk stratify, analyse site of recurrence and assess the role of radiotherapy. RNI is currently recommended for patients at high risk of recurrence, but prospective studies in other patients are needed to assess the role of RNI. Two randomised phase III trials have confirmed the safety and efficacy of 15-fraction hypofractionated radiotherapy, while 5-fraction super-hypofractionated radiotherapy to further shorten the course of radiotherapy is a hotspot of current research. The present study aimed to investigate whether RNI improves the outcome of intermediate-risk breast cancer patients; and to assess the efficacy and toxicity of 15-fraction hypofractionated and 5-fraction super-hypofractionated radiotherapy.