Long-term outcome after intraoperative radiotherapy as a boost in breast cancer.

Purpose: To investigate long-term oncological outcome and incidence of chronic side effects in patients with breast cancer and intraoperative radiotherapy given as an upfront boost (IORT boost).

Methods: Retrospective analysis of 400 patients with an IORT boost with low-energy X‑rays (20 Gy), subsequent whole-breast irradiation (46-50 Gy), and annual oncological follow-up. Side effects were prospectively evaluated (LENT-SOMA scales) over a period of up to 15 years.