Postmastectomy Radiation Therapy Bolus Associated Complications in Patients Who Underwent 2-stage Breast Reconstruction

PURPOSE: This study aimed to evaluate the association of bolus and 2-stage breast reconstruction complications, and whether the dosimetric advantage translates into improvements in local control. METHODS AND MATERIALS: We retrospectively analyzed data from 2008 to 2019 of women who underwent a mastectomy and a planned 2-stage breast reconstruction, followed by adjuvant radiation therapy. We reviewed all data from medical records and radiation plans regarding patient characteristics, diagnoses, surgeries, complications, pathology, staging, systemic therapy, radiation therapy, and outcomes, and compared complication rates according to bolus usage. RESULTS: A total of 288 women, age 25 to 71 years, were included in the study. Of these women, 6 were treated with daily bolus and 19 with alternate days bolus, totaling 25 of 288 patients (8.7%) in the bolus group. A total of 226 patients (78.5%) had the second stage performed. The median follow-up time was 61 months. The rates for 5-year overall survival and locoregional control were both 97%, and the metastasis-free rate was 83%. In the first stage, 6.25% of patients in the entire cohort had an infection and 4.2% had implant loss. Daily bolus significantly increased the risk of expander infection (hazard ratio [HR]: 10.3; 95% confidence interval [CI], 1.7-61.8) and loss (HR: 13.89; 95% CI, 2.24-85.98), but alternate-day bolus showed a nonsignificant increase for expander infection (HR: 1.14; 95% CI, 0.14-9.295) and loss (HR: 1.5; 95% CI, 0.19-12.87). Bolus was not associated with second-stage complications or local-regional failure. Local infection and implant loss were more frequent in the second than in the first stage (5.2% vs 10.2% and 4.2% vs 12.8%, respectively). CONCLUSIONS: Skin bolus significantly increased first-stage breast reconstruction complications (infection and reconstruction failure). Despite the small sample size and the need for future studies, these findings need to be taken into consideration when planning treatment and reconstruction, and recommendations should be individualized.