Impact of intraoperative radiotherapy

Background: Breast-conserving surgery (BCS) followed by adjuvant whole-breast external beam radiotherapy (WBRT) is a standard treatment for early-stage breast cancer, effectively reducing local recurrence and improving survival. However, WBRT involves a prolonged treatment schedule and may lead to adverse effects and reduced patient compliance. Intraoperative radiotherapy (IORT), as a form of accelerated partial breast irradiation (APBI), offers a shorter treatment course by delivering a single dose of radiation during surgery. Although randomized controlled trials suggest comparable survival outcomes between IORT and WBRT in selected patients, real-world evidence is limited. This study aimed to compare the effects of IORT and WBRT on survival outcomes in early-stage breast cancer patients who underwent BCS, using a population-based dataset. Methods: Data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2019. Patients who received either IORT or WBRT after BCS were included. Overall survival (OS) and cancer-specific survival (CSS) were assessed using Kaplan-Meier methods. Cox proportional hazards regression was performed to identify independent prognostic factors. Results: There was no statistically significant difference in OS and CSS between the IORT and WBRT groups. Factors associated with worse survival included older age, T2 stage, and higher tumor grade (all P<0.01). Positive estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status were significantly associated with improved survival (all P<0.01). Conclusions: IORT is an effective alternative to WBRT with equivalent long-term survival. IORT may be considered for eligible patients based on age, tumor size, receptor status, and grade. Prospective studies are warranted to optimize the selection criteria.