SP31. Autologous Free Flap Outcomes in Patients Following Postmastectomy Radiation Therapy Based on Radiation Dose: Systematic Review and Meta-analysis

PURPOSE: Changes in post-mastectomy radiation therapy (PMRT) dosage schedule have led to the development of the hypofractionated radiotherapy technique (HRT This approach allows patients to receive fewer radiotherapy sessions with higher doses in each session compared to the traditional dose of radiotherapy, known as conventional radiotherapy (CRT). This study hypothesized that the complication rate associated with HRT would be lower than those associated with CRT in patients undergoing autologous free flap breast reconstruction. METHODS: This study followed Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A search of EMBASE and Ovid MEDLINE databases was conducted from January 2003 to December 2023. The main search terms were synonyms of ‘radiation,’ ‘autologous,’ and either ‘immediate’ and/or ‘delayed’. Two authors screened each study. Exclusion criteria included articles without a radiation protocol and dose. Postoperative outcomes and complications were collected and analyzed. RESULTS: 454 papers were collected from the search. 237 duplicates were removed. Out of 238 studies that underwent abstract screening, 112 underwent full-text screening. 19 studies were extracted, which included 23 CRT and 3 HRT groups. Out of these groups, 127 flaps (8.4%) were treated with HRT, and 1378 flaps (91.6%) were treated with CRT. The HRT groups had significantly fewer post-operative complications than the CRT group (12.6% and 36.6% respectively, p-value<0.001). Split incidence of complications showed variable significant differences among the groups. Fat necrosis and hematoma rates were significantly lower in HRT (7.9% to 16.1%, p-value<0.001, and 0% to 6.1%, p-value<0.001 respectively). Revisions for aesthetic reasons were significantly lower in HRT (35.4% to 41.3%, p-value<0.001). CONCLUSION: Our study demonstrated that HRT yields more favorable outcomes than CRT. Advancements in radiotherapy techniques showed the potential to improve breast reconstructive outcomes. Future interprofessional collaboration between radiation oncologists, breast, and plastic surgeons should be encouraged to identify the safest treatment approaches.