Impact of Postmastectomy Radiation Therapy in Prepectoral Versus Subpectoral Implant-Based Breast Reconstruction.

[BACKGROUND] This study aimed to compare the impact of postmastectomy radiation therapy (PMRT) on outcomes after prepectoral versus subpectoral implant-based breast reconstruction with local deepithelialized dermal flap and acellular dermal matrix (ADM).

[METHODS] From 2010 to 2017, 274 patients (426 breasts) underwent prepectoral reconstruction. In this group, 241 patients (370 breasts) were not exposed to PMRT, whereas 45 patients (56 breasts) were exposed to PMRT. Of 100 patients (163 breasts) who underwent partial subpectoral reconstruction, 87 (140 breasts) were not exposed to PMRT, whereas 21 patients (23 breasts) were exposed. The outcomes were assessed by comparing complication rates between the pre- and subpectoral groups.

[RESULTS] A higher rate of capsular contracture was found for the prepectoral patients with PMRT than for those without PMRT (16.1 vs 3.5%; p = 0.0008) and for the subpectoral patients with PMRT than for those without PMRT (52.2 vs 2.9%; p = 0.0001). The contracture rate was three times higher for the subpectoral patients with PMRT than for the prepectoral patients with PMRT (52.2 vs 16.1%; p = 0.0018). In addition, 10 (83.3%) of 12 cases with capsular contracture in the subpectoral cohort that received PMRT were Baker grades 3 or 4 compared with only 2 (22.2%) of 9 cases of the prepectoral group with PMRT (p = 0.0092).

[CONCLUSIONS] The patients undergoing subpectoral breast reconstruction who received PMRT had a capsular contracture rate three times greater with more severe contractures (Baker grade 3 or 4) than the patients receiving PMRT who underwent prepectoral breast reconstruction.