Comparison of IORT (Radical and Boost Dose) and EBRT in Terms of Disease-Free Survival and Overall Survival according to Demographic, Pathologic, and Biological Factors in Patients with Breast Cancer.

Background: The standard treatment for breast cancer is breast-conserving surgery (BCS) with radiotherapy. If external beam radiation therapy (EBRT) can be safely replaced with intraoperative radiotherapy (IORT), it will help patients to save their breast and to have equivocal or better results in DFS and overall survival (OS).

Methods: A total of 2022 patients with breast cancer treated during 6 years were enrolled in the current study. A total of 657, 376, and 989 patients received EBRT, radical, and boost dose by IORT, respectively, according to the IRIORT consensus protocol. The primary endpoint was recurrence and death. The secondary endpoint was the role of variables in recurrence and death.

Results: With a mean follow-up of 34.5 and 40.18 months for the IORT and EBRT groups, respectively, there was a significant difference in DFS between electron boost and X-ray boost groups (P=0.037) and the electron radical group compared with EBRT (P=0.025), but there was no significant difference between other boost and radical groups in DFS and OS.

Conclusions: IORT can be a preferred treatment modality because of its noninferior outcomes, and in some special conditions, it has superior outcomes compared to EBRT, particularly in delivering radical dose with IORT.