Breast-conserving surgery is often performed for early-stage breast cancer with breast-conserving conditions, and 5 weeks of whole-breast radiotherapy is often required after breast-conserving surgery. In clinical practice, some patients give up radiotherapy due to busy work schedule, inconvenient transportation and old age, which increase the chance of recurrence, while some patients with low grade malignancy may be over-treated due to the use of whole breast radiotherapy, and about 90% of local recurrence of breast cancer occurs in the adjacent areas of the primary tumor. This requires clinicians to find an alternative to whole-breast radiotherapy that is precise, short, inexpensive, and equivocal, and single-site intraoperative radiotherapy was developed. The first lymph node in the ipsilateral axilla of breast cancer is also called the sentinel lymph node. If there is no metastasis in the biopsy of the sentinel lymph node, the axilla may not be cleared, which can avoid various complications of axillary lymph node clearance, such as shoulder joint dysfunction, edema and abnormal sensation of the affected limb, and subcutaneous fluid accumulation. So which cases can be suitable for breast-conserving surgery? 1.Tumor less than 3cm: the ratio of tumor size to breast. If the tumor is too large, the resection area must increase accordingly, and for Chinese women with less full breasts, the effect of breast preservation cannot be achieved; while if the resection area is reduced, the tumor is often not completely removed and may cause breast cancer recurrence. Breast-conserving surgery is generally recommended for women with less than 3 cm and a certain breast size. Some breast cancer patients are also suitable candidates for breast-conserving surgery if their breast lumps shrink to less than 3cm or cannot be felt at all after neoadjuvant chemotherapy. 2. The tumor location should be some distance away from the nipple areola: for example, behind the nipple areola is generally not suitable for breast-conserving surgery. At the same time, the lump should be far away from the nipple areola, which is more conducive to the perfect shape of the breast after surgery. 3.No multiple lesions: Multiple lesions in the breast are also not suitable for breast-conserving surgery, because in this case, even after breast-conserving surgery, there is no guarantee that no tumor remains in the breast, so breast magnetic resonance examination can be done to understand the situation in the breast before surgery. 4. No lymph node enlargement: Of course, breast-conserving surgery is also not suitable for those with large lumps, edema and clearly enlarged axillary lymph nodes. Currently, breast-conserving surgery only accounts for about 20% of all breast cancer patients in China, but in reality, some patients still have concerns about breast-conserving surgery, and the biggest reason that prevents them from choosing breast-conserving surgery is the therapeutic effect of breast-conserving surgery. Most patients also think that it is safer to cut off the whole breast, and that a total mastectomy is “one and done”, and that if you cut it off, you will never have to worry about recurrence. This is actually a false belief and lacks evidence to support it. Changes in the treatment of breast cancer have occurred as the understanding of the nature of breast cancer has increased. With the development of comprehensive breast cancer treatment, adjuvant radiotherapy, chemotherapy, and endocrine therapy, these treatments have been added to provide greater options for surgical approaches. Breast-conserving surgery is firstly to ensure complete and thorough excision of the mass, and on top of that, adjuvant postoperative radiotherapy, chemotherapy or endocrine therapy, the therapeutic effect is fully equivalent to modified radical surgery. Many large international clinical trials have also confirmed that the overall survival rate of patients after breast-conserving surgery is virtually indistinguishable from that of patients with total mastectomy. The clinical approach of professional pre-surgical evaluation, standardized surgical and post-operative adjuvant treatment makes breast-conserving surgery safe and reliable. These encouraging results strengthen the resolve of patients eligible for breast-conserving surgery to pursue a quality of life.