Breast cancer is the most common malignant tumor in women. About 1.4 million women worldwide develop breast cancer every year, and most of them need to undergo surgical treatment. Traditional (modified) radical breast cancer surgery requires complete removal of the breast and clearance of the axillary lymph nodes, which is traumatic and slow to recover, and some patients may experience flap necrosis and even require skin grafting. However, the trauma is not only limited to the body, but as a woman, the loss of the breast also causes great damage psychologically. In order to achieve treatment with less trauma, breast-conserving surgery has gradually developed and has now become a very mature technique. During the operation, only the breast cancer and some of the surrounding glandular tissues are removed, and it is ensured that no cancer cells remain in the surrounding tissues (i.e. the lump is completely removed), and the gland is re-sutured through the breast oncoplastic technique so that the breast still retains a relatively normal appearance. At the same time, combined with the anterior sentinel lymph node biopsy technique, some patients who are eligible can also be treated without clearing the axillary lymph nodes, thus allowing the function of the upper extremity to be well protected. However, not all patients are suitable for breast conservation and need to meet some of the following conditions: 1. Tumor size: Currently most hospitals consider the tumor to be within 75px. If the breast is larger, the tumor >75px or even ≥125px, the tumor shrinks after preoperative neoadjuvant chemotherapy, and the expanded removal of the tumor does not affect the breast shape, breast-conserving treatment is still feasible; if the breast development is too small, the ratio of tumor size to breast size should be considered, and breast-conserving surgery requires that the tumor can still retain a better breast shape after removal as specified. 2.Tumor location: the tumor is located in the peripheral quadrant, and the edge of the tumor is ≥50px from the edge of the areola. 3.Pathological type: no special requirements, but inflammatory breast cancer should be excluded. 4.Can guarantee the completion of breast-conserving treatment plan, such as post-operative radiotherapy, etc. 5.Patients have breast-conserving requirements. The following conditions are not suitable for breast conservation: 1. Multiple primary lesions and located in different quadrants of the breast, or mammograms suggesting diffuse microcalcifications in the breast with malignant features. 2, The affected breast has received radiation therapy. 3.Pregnancy is an absolute contraindication to breast radiation, but breast-conserving surgery can be performed in the second trimester of pregnancy, and radiation therapy can be performed after delivery. 4. Breast-conserving surgery specimens with positive cut margins cannot reach negative cut margins even after extended excision, which means partial excision is not complete.