Prognostic Impact of Postoperative Radiotherapy and Associated Risk Factors in Postmastectomy Breast Reconstruction Patients: A Dual-Center Real-World Study

Objective: Postmastectomy breast reconstruction (PMBR) is a well-established treatment modality with significant aesthetic value, and postmastectomy radiotherapy (PMRT) is an equally essential therapeutic approach. This study evaluates the impact of various factors on the prognosis of PMBR patients by comparing those who received radiotherapy with those who did not. Methods: A total of 2,581 breast reconstruction patients treated at Tianjin Cancer Hospital and Henan Cancer Hospital up to June 2024 were included. Clinical data were obtained from the hospital HIS system, and clinical prognostic differences among different subgroups were analyzed using multiple real-world statistical methods. All procedures performed in this study were conducted in accordance with the relevant guidelines and regulations. Informed consent was obtained from all participants and/or their legal guardians, and institutional ethical approval was secured. Results: Higher histological grade (HR=1.75, 95% CI: 1.35-2.27, p=0.002), T stage (HR=2.12, 95% CI: 1.68-2.67, p<0.001), and N stage (HR=2.45, 95% CI: 1.89-3.19, p<0.001) were identified as significant high-risk factors for overall survival (OS) in PMBR patients. For progression-free survival (PFS), significant high-risk factors included neoadjuvant therapy (HR=1.58, 95% CI: 1.21-2.07, p=0.003), use of tissue expanders (HR=1.41, 95% CI: 1.09-1.82, p=0.009), and higher T stage (HR=2.09, 95% CI: 1.66-2.63, p<0.001) and N stage (HR=2.35, 95% CI: 1.85-3.00, p<0.001).Radiotherapy was not identified as an independent high-risk factor for OS or PFS in PMBR patients (p=0.137). However, combined radiotherapy reduced the risk of PFS events in PMBR patients with advanced T stage (HR=0.72, 95% CI: 0.58-0.90, p=0.004) or N stage (HR=0.79, 95% CI: 0.65-0.97, p=0.023). Radiotherapy also improved long-term aesthetic satisfaction and patient survival experience by reducing repair rates for both flap (HR=0.63, 95% CI: 0.51-0.79, p<0.001) and implant reconstructions (HR=0.68, 95% CI: 0.54-0.85, p=0.001). Caution is advised when using two-stage implant reconstruction, as it may be associated with poorer repair rates (HR=1.89, 95% CI: 1.47-2.43, p<0.001), potentially leading to reduced long-term aesthetic satisfaction. Conclusion: Radiotherapy is a valuable treatment option for PMBR patients, significantly reducing prognostic risks in certain scenarios and improving aesthetic outcomes.