D153. Prepectoral Versus Subpectoral Tissue Expander Placement on Free Flap Outcomes in Delayed-immediate Autologous Breast Reconstruction

PURPOSE: Recent data has suggested benefits to prepectoral tissue expander (TE) placement as compared to the traditional subpectoral approach. We sought to compare prepectoral versus subpectoral TE in autologous breast reconstruction by comparing complications, patient reported outcomes and aesthetic results. METHODS: This was a retrospective study of patients who underwent TE and free flap reconstruction between 2016-2020 at MD Anderson. The Breast-Q was administered to all patients. An aesthetic survey was administered for aesthetic comparisons. RESULTS: We identified a total of 184 cases on 151 patients. Prepectoral was more common (62.5% vs 37.5%). The groups were comparable except for higher BMI (p=0.038) and adjuvant radiotherapy (p<0.001) in the subpectoral group. There were no significant differences in TE complications or postoperative flap complications. There was a trend toward increased microvascular complications in the subpectoral group (10.1% vs 3.5%, p=0.105), which persisted in the adjuvant radiation subgroup (subpec:16.2% vs prepec:3.6%, p=0.130). The breast Rasch scores (prepec:73.6 vs subpec:68.9, p=0.401) and chest Rasch scores (prepec: 80.5 vs subpec: 78.9, p=0.999) were found to be equivalent, which persisted in the adjuvant radiation subgroup (p=0.168, p=0.99). The aesthetic survey showed superior results in non-radiated patients for both prepectoral and subpectoral reconstructions (p=0.000). In non-radiated patients, both groups were equivalent (p=0.212); whereas, subpectoral was slightly superior in radiated patients (p=0.034). CONCLUSION: Our data suggest that prepectoral tissue expander placement prior to free flap surgery is a valid alternative to subpectoral placement with a trend toward less microvascular complications and comparable PROMs and aesthetic results.