The indication of radiotherapy after radical breast cancer surgery is a question that we often encounter, do we need radiotherapy after radical breast cancer surgery? What are the indicators to determine whether she needs radiotherapy or not? Firstly, if the size of the tumor is >5cm, it is an indication for radiotherapy. The second point is the condition of axillary lymph nodes. If the number of axillary lymph node metastases is >4, this is an absolute indication for radiotherapy, but some new research data show that after modified radical breast cancer surgery, if the number of positive axillary lymph node metastases is >1, it is also an indication for radiotherapy. The third point is the evaluation of the tumor before surgery, such as tumor invasion of the skin or tumor invasion of the chest wall is also an indication for postoperative radiotherapy. The last aspect is the situation during surgery, according to the situation during surgery to determine whether chemotherapy or radiotherapy is needed, if there is tumor residue during surgery, if there is suspicion that the tumor is not cleanly removed, or if there is suspicion that the base of the tumor is not sufficiently resected, or if there is tumor residue as indicated by the cryo-examination during surgery, it is also an indication for radiotherapy, and there are other special circumstances including molecular typing, which are also included in the indication for radiotherapy. There are also other special conditions, including molecular typing, which are also included in the indications for radiotherapy.