Intra-Operative Electron Radiation Therapy (IOERT) Anticipated Boost in Breast Cancer Treatment: An Italian Multicenter Experience

Simple Summary In breast cancer, IOERT represents an attractive therapeutic option to deliver a boost directly on the tumor bed during surgery with all the relative radiobiological advantages. According to the literature, the present multicenter research demonstrates the safety and efficacy of this treatment using a large group of patients treated in daily clinical practice. Between January 2011 and March 2018, 797 patients were evaluated. Median follow-up was 57 months (range 12-109 months). Acute toxicity >= G2 occurred in 179 patients (22.46%). No patients reported late toxicity > G2. Obj-cosmetic result was excellent in 45%, good in 35%, fair in 20% and poor in 0% of cases. Subj-cosmetic result was excellent in 10%, good in 20%, fair in 69% and poor in 0.3% of cases. At 5 years, in-field LC was 99.2% (95% CI: 98-99.7); out-field LC 98.9% (95% CI: 97.4-99.6); DFS 96.2% (95% CI: 94.2-97.6); OS 98.6% (95% CI: 97.2-99.3). In breast cancer, the use of a boost to the tumor bed can improve local control. The aim of this research is to evaluate the safety and efficacy of the boost with intra-operative electron radiotherapy (IOERT) in patients with early-stage breast cancer undergoing conservative surgery and postoperative whole breast irradiation (WBI). The present retrospective multicenter large data were collected between January 2011 and March 2018 in 8 Italian Radiation Oncology Departments. Acute and late toxicity, objective (obj) and subjective (subj) cosmetic outcomes, in-field local control (LC), out-field LC, disease-free survival (DFS) and overall survival (OS) were evaluated. Overall, 797 patients were enrolled. IOERT-boost was performed in all patients during surgery, followed by WBI. Acute toxicity (>= G2) occurred in 179 patients (22.46%); one patient developed surgical wound infection (G3). No patients reported late toxicity >= G2. Obj-cosmetic result was excellent in 45%, good in 35%, fair in 20% and poor in 0% of cases. Subj-cosmetic result was excellent in 10%, good in 20%, fair in 69% and poor in 0.3% of cases. Median follow-up was 57 months (range 12-109 months). At 5 years, in-field LC was 99.2% (95% CI: 98-99.7); out-field LC 98.9% (95% CI: 97.4-99.6); DFS 96.2% (95% CI: 94.2-97.6); OS 98.6% (95% CI: 97.2-99.3). In conclusion, IOERT-boost appears to be safe, providing excellent local control for early-stage breast cancer. The safety and long-term efficacy should encourage use of this treatment, with the potential to reduce local recurrence.