IOERT in Breast Cancer: Results of Ten-Year Follow-Up in an Italian Experience Confirm High Local Recurrence Rate

Purpose: Accelerated Partial Breast Irradiation (APBI) using Electron-Beam Intraoperative Radiation Therapy (IOERT) in carefully selected breast cancer patients is usually performed as single dose after conserving surgery. IOERT has demonstrated a low incidence of complications without compromising oncological outcomes. In our study we evaluated the rate of LR and progression free survival in a long-term follow-up. Patients and Methods: We performed IOERT with a 21 Gy single total dose referred to iso dose 90% in 322 selected patients for a total of 332 irradiated tumor lesions at the Breast Center of Pisa between January 2004 and May 2015. A close multidisciplinary follow-up was regularly conducted every 6 months. We evaluated the data at the end of 2020. Results: At a median follow-up of 10 years, 27 patients had in-field breast recurrence (8.1%) while considering a 5-year follow-up, we observed 16 LR (4.8%). According to our data, although a 5-year follow-up demonstrates an acceptable relapse rate in patients treated with IOERT, the assessed LR rate over a longer follow-up period reveals the occurrence of a significant number of relapses. Our results are consistent with the more important ones revealed by randomized trials. Conclusion: IOERT remains an acceptable approach to be considered only in carefully selected patients at particularly low risk of relapse (small, well-differentiated, luminal-A tumors, with a low Mib-1) even though the LR rate in a longer follow-up is significantly higher than standard RT.