Dosimetric and Clinical Factors Associated With Breast Reconstruction Complications in Patients Receiving Postmastectomy Radiation.

PURPOSE: Approximately 30% of women who receive postmastectomy radiation therapy in the setting of breast reconstruction suffer from reconstruction complications. This study aims to assess clinical and dosimetric factors associated with the risk of reconstruction complications after postmastectomy radiation therapy, with the ultimate goal of identifying a dosimetric constraint that can be used clinically to limit this risk. METHODS AND MATERIALS: We retrospectively identified 41 patients who underwent a modified radical or total mastectomy, followed by immediate or delayed reconstruction (autologous or implant-based) and radiation at a single institution between 2014 and 2020. Reconstruction complications were defined as a flap or implant failure, necrosis, capsular contracture, cellulitis/infection, implant rupture, implant malposition, leakage/rupture, unplanned operation, and hematoma/seroma. Clinical and dosimetric variables associated with complications were assessed with univariate analyses. RESULTS: Twelve patients (29%) suffered reconstruction complications, which led to a flap or implant failure in 5 patients. The median time to complication after reconstruction was 8 months. Thirty-two percent of patients with immediate and 20% with delayed reconstruction suffered a complication, respectively. There were no local failures. Smoking (P = .02), use of bolus (P = .03), and the percentage of the chest wall/reconstructed breast target volume that received ≥107% of the prescribed radiation dose (V107) > 11% (P = .03) were associated with increased complication rates. The complication rates were 42% when V107 > 11% versus 12% when V107 < 11%; 58% in smokers versus 17% in nonsmokers; and 42% with versus 7% without bolus. CONCLUSIONS: Plan heterogeneity appears to be associated with the risk of reconstruction complications. Pending further validation, V107 < 11% may serve as a reasonable guide to limit this risk. Further consideration should be given to the selective use of bolus in this setting and optimization of clinical factors, such as smoking cessation.