Evaluation of the Effectiveness and Safety of Laparoscopic Assisted Mastectomy With Preservation of Nipple and Areola, Immediate One-step Breast Reconstruction With Pectoral Muscle Prosthesis and Patch, and Simultaneous Autologous Fat Transplantation

Inclusion Criteria: 1. Women aged 18 to 70 years old; 2. In the first diagnosis of unilateral breast cancer patients, the maximum diameter of invasive tumor is ≤ 5cm, and there is no requirement for tumor size of carcinoma in situ in principle; 3. Patients undergoing preventive mastectomy are not allowed to be included in the study; 4. Clinical examination and auxiliary examinations suggest that the tumor is confined to the mammary gland and has not invaded the nipple areola complex, skin, or chest wall; 5. Clinical axillary lymph node negative (clinical physical examination and imaging suggest negative axillary lymph nodes; for suspected positive axillary lymph nodes, fine needle aspiration or hollow needle biopsy is required to confirm negative); 6. Sentinel lymph node biopsy negative; 7. Patients with low load positive axillary lymph nodes (isolated tumor cells, micro or macro metastases), but exempted from adjuvant radiotherapy after surgery; 8. Patients who are not suitable for breast conserving surgery or who are unwilling to undergo breast conserving surgery and plan to undergo laparoscopic assisted mastectomy with preservation of the nipple and areola, as well as immediate one-step breast reconstruction with a breast prosthesis combined with a chest muscle prosthesis and simultaneous fat transplantation; If frozen pathology or routine pathology indicates a positive posterior margin of the nipple, it is allowed to remove the nipple, but the areola must be preserved; 9. The volume of the prosthesis is less than 500cc; 10. During the observation period of the study, the affected side may consider re fat injection, but symmetrical surgery is not allowed on the healthy side; 11. ECOG score 0-1 points; 12. New adjuvant chemotherapy patients are allowed to be enrolled; 13. No smoking history or quitting smoking for at least 4 weeks; 14. The researcher determines that they are able to comply with the research protocol; 15. Those who participate in other clinical trials (including intervention or non intervention studies) at the same time and are judged by the researchers to not affect the study protocol can be enrolled normally; 16. After obtaining sufficient information, voluntarily participate and sign an informed consent form. Exclusion Criteria: 1. Specialized physical examination and/or auxiliary examination suggest that the tumor involves the nipple areola complex (including Paget's disease) or the skin; 2. Double breast cancer; 3. Bilateral breast reconstruction patients; 4. Patients who have undergone fat injection, breast augmentation with implants, and breast reduction surgery in the past; 5. Patients with incomplete immune function, poor control of diabetes and active smoking; 6. Patients with severe breast sagging; 7. Breast cup size ≥ E; 8. Accept two-step breast reconstruction using dilators/prostheses, autologous breast reconstruction, and breast reconstruction performed through open surgery; 9. Patients who have previously received and/or received postoperative radiotherapy for the reconstruction site or chest wall; 10. Patients who plan to undergo symmetrical surgery on the healthy breast during the visit period; 11. Patients with mental illnesses or abnormalities who are expected to be unable to independently complete the BREAST-Q scale; 12. Pregnant and lactating patients; 13. Poor compliance, unable to conduct relevant examinations and follow ups according to the trial requirements; 14. Suffering from serious accompanying diseases or other comorbidities that may interfere with planned treatment, or any other circumstances that the researcher deems unsuitable for the patient to participate in this study.