Abstract 120: Implant-Based Breast Reconstruction and the Timing of Adjuvant Radiotherapy: A Systematic Review and Meta-Analysis of Surgical Outcomes

Abstract

PURPOSE: Implant-based breast reconstruction is the most common type of reconstruction. Outcomes of breast reconstruction are worse following post-mastectomy radiation therapy (PMRT), however, the impact of factors like timing, duration and dosage remain poorly understood. The impact of the timing of PMRT relative to the course of reconstruction is perhaps one factor that can be potentially modified by reconstructive surgeons. The systematic review aims to evaluate surgical outcomes following implant-based reconstruction in the setting of PMRT. METHODS: A systematic review of the English literature published from 2000 to 2016 in the PubMed/MEDLINE electronic database was performed to identify all manuscripts reporting outcomes of implant-based breast reconstruction in patients receiving PMRT. Patients in each study were grouped by timing of PMRT relative to reconstructive course; whether radiotherapy was administered to a tissue expander or permanent implant. Primary outcomes of interest were the most major of complications: reconstructive failure and capsular contracture. Overall rates and associations were determined via established methods; effect sizes (z-values), risk ratios (RRs), and heterogeneity scores (I2) were calculated on meta-analysis using a random and fixed effect models. RESULTS: Twenty studies met our inclusion criteria for a total of 2,348 patients undergoing implant-based breast reconstruction treated with PMRT. Five studies (25%) were performed prospectively while the remaining 15 (75%) were performed retrospectively. Most studies represented Level III evidence (16/20, 80%). The remaining minority was equally comprised of Level II (2/20, 10%) and Level IV studies (2/20, 10%). Mean follow-up was 39.5 months with a minimum average of 14.5 months and a maximum average of 73.5 months. Mean time to tissue expander exchange for permanent implant was 10.1 months in the 12 studies reporting this information. Pooled analysis of all patients revealed a rate of reconstructive failure of 17.5% and a rate of Baker grade III/IV capsular contracture of 37.5%. Overall, compared to patients receiving PMRT to permanent implants, patients who had PMRT applied to tissue expanders experienced higher rates of reconstructive failure (20% vs. 13.4%, p=0.001), but lower rates of capsular contracture (24.5% vs. 49.4%, p=0.0001). Meta-analysis demonstrated consistent findings by revealing a large effect size of 1.82 (RR=1.99, 95% CI 0.95–4.20) for reconstructive failure and a smaller effect size of -0.34 (RR=0.87, 95% CI 0.39–2.00) for capsular contracture. CONCLUSION: Regardless of timing, PMRT applied to implant-based breast reconstruction was associated with an unacceptably high risk of adverse events. Surgeons should strongly consider alternative methods of breast reconstruction, such as autologous-based reconstruction, as an alternative for patients who will require radiotherapy as part of their treatment protocol.