Comparing Radiotherapy (RT) Late Toxicities to the Reconstructed DIEP Flap in Breast Cancer Patients Treated with Neoadjuvant RT (NART) vs. Post-Mastectomy RT (PMRT)

Abstract

<h3>Purpose/Objective(s)</h3> The use of PMRT in patients undergoing immediate Deep Inferior Epigastric Perforator (DIEP) flap reconstructions is well known to cause significant long-term toxicity such as flap contracture, fat necrosis and cosmetic detriment. This can lead to significant long-term pain and impact on quality of life (QOL) (Yun et al, 2018). On the other hand, NART prior to the DIEP reconstruction performed in our institution has been shown to have no detriment in safety and local control but the long-term impact on the DIEP reconstruction remains unclear (Chidley et al, 2021). The aim of this retrospective study is to compare the long-term consequences of NART followed by DIEP versus immediate DIEP with PMRT on the reconstruction. <h3>Materials/Methods</h3> Retrospective comparison of long-term toxicities was done on the patient cohort who underwent NART followed by DIEP reconstruction (from 03/2013 to 09/2019) and patients who had immediate DIEP reconstruction followed by RT (from 01/2013 to 05/2021). Clinical examination was performed to assess the presence of fat necrosis (graded using the Wagner classification et al. 2013) and flap contracture. Breast cosmesis was graded using the Kroll classification (Kroll et al, 1994). Statistical analysis was performed to identify the rate of cosmesis problem, fat necrosis and flap contracture between these two patient's cohorts. <h3>Results</h3> Total of 155 patients who underwent NART and 31 patients who went through PMRT were analyzed. The median age of each cohort is 48 and 49 respectively for NART vs PMRT (p=0.26). Majority of patients in the NART and PMRT cohort received 50.4Gy/28# (78.6% [121] vs 74.2% [23]). Median follow up for NART and PMRT group was 32.5 months and 28.8 months respectively. No difference in local control was reported (98.1% NART vs 100% PMRT). Patients who had NART reported a higher satisfaction rating with their cosmesis. This was reported as ‘excellent to good' in 96.1% for NART compared to 80.1% for PMRT p<0.001. In addition, the risk of developing a flap contracture was significantly increased in patients who had PMRT (1.9% NART vs 41.9% PMRT; p<0.001). This was described as minimal in 29% and moderate in 12.9%. The risk of developing fat necrosis rate was also significantly increased in patients who had PMRT (12.9% NART vs 19.4% PMRT; p<0.001). While all fat necrosis in the NART cohort was grade 2, 50% of patients in the PMRT cohort had pain as well (grade 4). <h3>Conclusion</h3> Our retrospective analysis suggests that PMRT following immediate DIEP has significantly higher risk of late toxicities compared to NART followed by DIEP reconstruction. Whether this translates to a meaningful impact on QOL can only be determined by a randomized study.