2909 - Comparing Post-Mastectomy Radiotherapy (PMRT) Late Toxicities in Autologous vs. Allogeneic Breast Reconstructed Patients

Purpose/Objective(s): Immediate breast reconstruction options for post mastectomy patients with locally advanced breast cancer patients include autologous reconstruction (AR) or allogeneic implant [direct to implant (DTI)]. Post mastectomy radiotherapy (PMRT) plays an integral role in reducing locoregional recurrence and improving survival (EBCTCG). However, the use of PMRT in reconstructed breasts may cause long-term toxicity such as cosmetic detriment, fat necrosis, contracture and implant failure. This can lead to chronic pain and negatively impact quality of life (Yun). The aim of this retrospective study is to compare the long-term consequences of PMRT in patients undergoing immediate autologous versus allogeneic breast reconstruction.

Materials/Methods: A retrospective comparison of long-term toxicities was conducted on a cohort of patients who underwent immediate AR or DTI followed by PMRT between January 2013 and June 2024. Clinical evaluations were performed to assess breast cosmesis (Kroll), the presence of fat necrosis (Wagner), flap or capsular contracture (Haran), and the need for implant removal or replacement with autologous tissue. Statistical analysis was employed to determine the incidence of these toxicities within each group. Results: A total of 68 patients with AR and 45 patients with DTI were analyzed. The mean age was 50 years (SD = 8) for AR and 46 years (SD = 10) for DTI. The median follow-up period was 39 months. The majority of AR (81%) and DTI (84%) patients received a PMRT dose of 50.4Gy over 28 fractions. Four DTI patients were excluded from the late toxicity assessment due to implant removal prior to radiation (2) or our first scheduled late toxicity assessment (2). One patient developed an implant infection post-radiation and the second had early local recurrence (1 patient). Patients who underwent AR reported significantly higher satisfaction with breast cosmesis, with 84% rating their results as ‘good’ or ‘excellent,’ compared to only 32% with DTI (p < 0.001). Capsular contracture was observed in all DTI patients, with 8 (19%) and 11 (27%) patients experiencing grade 3 and 4 contractures respectively. Of these, 9 required implant removal (2 with grade 3 and 7 with grade 4 contractures). In contrast, less than half (49%) of AR patients developed flap contracture, with moderate contracture being the highest grade (7%). AR patients were at risk of fat necrosis, with 11 (16%) patients identified. In total, implant failure occurred in 12 (27%) patients with DTI with none reported for AR.

Conclusion: The study suggests that AR is a more favorable option for patients who require RT, as it results in no implant failure with better cosmetic outcomes and fewer complications compared to DTI.

Abstract 2909 - Table 1