The treatment of breast cancer patients does not always require mastectomy. Some patients can achieve the same therapeutic effect as mastectomy through breast-conserving surgery plus radiotherapy. Breast-conserving treatment is suitable for: 1. Early stage breast cancer in clinical stage I and II. It is especially suitable for early stage breast cancer patients whose maximum tumor diameter does not exceed 3cm, and whose breasts have appropriate volume and can maintain good breast shape after surgery. 2.Stage III patients (except inflammatory breast cancer) can also be carefully considered after preoperative chemotherapy downstaging. Absolute contraindications to breast-conserving treatment: 1. Patients who have received previous radiotherapy to the breast or chest wall on the same side. 2. Extensive lesions or confirmed multicentric lesions, difficult to achieve negative cut margins or ideal shape. 3.Patients who have positive margins after extensive local excision and still cannot guarantee negative pathological margins after re-excision. 4.The patient refuses to have breast preservation surgery. 5.Inflammatory breast cancer. Relative contraindications of breast-conserving treatment: 1. Active connective tissue disease, especially scleroderma and systemic lupus erythematosus or collagen vascular disease, and poor tolerance to radiotherapy. 2.Tumor diameter greater than 5cm. 3.Tumor located in the central region of the breast, nipple Paget’s disease.