Prospective Evaluation of the Efficacy and Safety of Prepectoral Immediate One-Stage Prosthetic Breast Reconstruction Versus Two-Stage Expander/Prosthesis Reconstruction in Postoperative Adjuvant Radiotherapy Breast Cancer Patients

This study is a prospective, double-cohort study. It plans to enroll more than 104 patients with cT1-3N0-3M0 breast cancer for immediate prepectoral muscle prosthesis reconstruction or two-step breast reconstruction with expander/prosthesis, and they will receive postoperative radiotherapy. Record the changes of BREAST-Q scores of the patients before and after the operation, as well as information such as postoperative complications and capsular contracture.

The primary endpoint was the BREAST-Q score at 12 months after the operation. The secondary endpoints included the success rate of breast reconstruction, surgical complications, cosmetic effects of the breast evaluated by doctors, the occurrence of capsular contracture, nipple and skin sensation, and tumor safety.

Inclusion Criteria:

1. women aged 18 to 70；
2. Newly diagnosed breast cancer patients showing no evidence of distant metastasis on clinical examination and diagnostic workup；
3. adjuvant radiotherapy is required;
4. Patients scheduled to undergo nipple-sparing mastectomy (NSM) or skin-sparing mastectomy (SSM) with immediate prepectoral implant-based reconstruction (via open, endoscopic, or robotic approach) require adjuvant radiotherapy AFTER permanent implant placement; OR Patients scheduled for NSM/SSM with two-stage tissue expander/implant reconstruction (with expander placement in either submuscular or prepectoral plane) receive radiotherapy WITH the tissue expander in situ, followed by exchange for permanent implant ≥6 months post-radiotherapy (expander position: submuscular/prepectoral acceptable; surgical approach: open/endoscopic/robotic acceptable);
5. Patients are eligible regardless of whether mesh is used in the reconstruction surgery;
6. Patients with severe breast ptosis are eligible;
7. During the study observation period, lipofilling is permitted on the affected breast and symmetrization procedures on the contralateral breast in both cohorts;
8. ECOG performance status 0-1;
9. Patients receiving neoadjuvant chemotherapy (NACT) are eligible;
10. Bilateral breast reconstruction is permitted;
11. No smoking history OR smoking cessation ≥4 weeks prior to enrollment;
12. Investigator-confirmed protocol compliance capability;
13. Concurrent participation in other interventional/non-interventional trials is allowed if deemed non-interfering by the investigator;
14. Voluntarily participate and sign the informed consent form after comprehensive understanding.

Exclusion Criteria:

1. Stage IV (metastatic) breast cancer;
2. No prior radiotherapy post-mastectomy;
3. History of ipsilateral chest wall/axillary radiation therapy;
4. Immunodeficiency, poorly controlled diabetes (HbA1c >7%), or active tobacco use;
5. Inflammatory breast cancer (cT4d);
6. Autologous-based breast reconstruction or delayed reconstruction;
7. Severe cardiopulmonary/hepatic/renal comorbidities contraindicating surgery/radiotherapy (ASA class ≥III);
8. Psychiatric disorders precluding independent BREAST-Q completion;
9. Pregnancy or lactation;
10. Documented history of protocol non-adherence;
11. Life-limiting comorbidities interfering with treatment OR investigator-determined ineligibility.

Treatment-naïve women with unilateral primary breast cancer (clinical stage cT1-3N0-3M0) scheduled for immediate prepectoral direct-to-implant reconstruction OR tissue expander/implant two-stage reconstruction, followed by adjuvant radiotherapy.