Breast reconstruction-related complications from postmastectomy radiation therapy in stage II–III breast cancer: sub-analysis of a multi-institutional observational study (Reborn-03)

Background Although postmastectomy radiation therapy (PMRT) is a standard treatment for high-risk breast cancer, it adds the risk of complications after breast reconstruction (BR). Methods This multi-institutional cohort study included patients with stage II–III breast cancer—defined as tumor size ≥ 5 cm, lymph node involvement, and/or skin/chest wall invasion—who underwent immediate or delayed BR after mastectomy between January 2008 and December 2018. We retrospectively investigated the relationship between PMRT and BR-related complications after adjusting for patient characteristics and BR method. Results Among 1138 patients (1101 immediate and 37 delayed BR), 427 (37.5%) underwent PMRT. The cohort included 238 (20.9%) patients with tumors ≥ 5 cm, 725 (63.7%) with 1–3 lymph node metastases, and 257 (22.6%) with ≥ 4. BR methods included 750 prosthetic, 385 autologous, and 3 fat graft procedures. The overall complication rates were 25.2% and 31.5% in the non-PMRT and PMRT groups, respectively ( p = 0.028). In prosthetic BR, capsule contracture ( p < 0.001) and infection ( p = 0.014) were more frequent in the PMRT than the non-PMRT group, whereas no significant difference was observed in complication rates between two groups in autologous BR. Multivariate analysis identified PMRT as an independent risk factor for BR-related complications (odds ratio, 1.47; p = 0.032). The reoperation rate was similar in two groups. Conclusions PMRT was associated with an increased incidence of BR-related complications in prosthetic BR, but not with reoperation, irrespective of the reconstruction method.