Radiotherapy after breast-conserving surgery for early-stage breast cancer is generally recommended to begin 3 to 4 weeks after surgery, depending on the individual. Breast cancer is a malignant neoplastic disease originating from the epithelial cells of the breast. In principle, most patients undergoing breast-conserving surgery need radiotherapy. Generally, it is recommended to start radiotherapy 3~4 weeks after breast-conserving surgery for early-stage breast cancer, but should not exceed 8 weeks after surgery. Usually, doctors in the clinic will formulate an appropriate treatment plan according to the patient’s condition. Radiotherapy uses radiation to kill cancer cells, which can reduce tumor metastasis and recurrence to a certain extent, and improve the survival rate of patients and the effect of surgery. The prognosis of breast cancer is closely related to the clinical stage, and most of the early breast cancer patients have good prognosis after standardized treatment. Patients need to go to the hospital for follow-up on time so that doctors can understand the changes in their conditions.