Intraoperative radiotherapy (IORT) versus whole-breast external beam radiotherapy (EBRT) in early stage breast cancer: results from SEER database

Purpose: Intraoperative radiotherapy (IORT) has emerged as an alternative to whole-breast external beam radiotherapy (EBRT) for early breast cancer. This study aimed to investigate the risk factors for survival after IORT or whole-breast EBRT in breast cancer patients. Materials and methods: Breast cancer patients undergoing IORT or whole-breast EBRT were included from the surveillance, epidemiology, and end results database. Risk factors for overall survival (OS) and cancer-specific survival (CSS) were identified by Cox proportional hazards regression analysis. Results: The IORT and EBRT groups did not differ significantly in OS and CSS. T2 stage (tumor size > 2 cm) was associated with poorer OS (aHR 3.49, 95% CI 1.05–11.62, P = 0.042), whereas ER-positive tumors were associated with better OS (aHR 0.26, 95% CI 0.09–0.76, P = 0.014). Conclusion: IORT was not inferior than EBRT considering the OS and CSS in the short-term follow-up of early breast cancer. It may be a reasonable alternative to EBRT for early breast cancer in select patients with favorable tumor size and receptor status, given the need for long-term monitoring of local control and radiation toxicity.