Conditions for breast preservation 1.Tumor is relatively small, usually 2~3 cm is better, appropriate ratio of tumor and breast, good postoperative appearance; 2.No skin and chest wall invasion; 3.Single mass, more than 2 cm from the areola; 4.Clinical stage within 2 stages; 5.No multiple mud-like calcifications on mammography; 6.Patients have a strong desire to preserve breast; 7.Hospital has preoperative and postoperative chemotherapy team and experience; 8.Hospital has preoperative and postoperative chemotherapy team and experience 8.The hospital has post-breast-conserving radiotherapy facilities and physicians with radiotherapy experience; 9.The biological behavior of the tumor is low-grade malignant; 10.The pathology is non-invasive lobular carcinoma, and lobular carcinoma itself is a multicentric lesion. Contraindications 1.Large tumor, small breast, unsatisfactory breast-conserving appearance; 2.Multiple axillary lymph node metastases; 3.Patients with multiple foci and late stage; 4.Patients without the will to preserve breast; 5.Patients with breast cancer during pregnancy; 6.Patients with collagen disease; 7.Area where medical institutions do not have radiotherapy facilities and technical strength.