Intraoperative or postoperative radiotherapy boost in high-risk breast cancer: a matched-pair analysis
- 1Department of Radiation Oncology, University Hospital Bonn, University of Bonn, Venusberg Campus 1, Building 55, 53127 Bonn, Germany
- 2Department of Radiotherapy, Instituto Nacional de Enfermedades Neoplasicas, Lima, Peru
- 3Department of Radiation Oncology, Oncosalud-Auna, Lima, Peru
Abstract
Purpose: The optimal boost technique following breast-conserving surgery for patients with high-risk early breast cancer remains controversial. This study compared oncologic outcomes following an intraoperative radiotherapy (IORT) boost using low-energy X‑rays with those of a conventional external beam radiotherapy (EBRT) boost in a matched-pair cohort.
Methods: Patients treated with breast-conserving surgery followed by either an upfront IORT boost (20 Gy prescribed to the applicator surface) or a postoperative EBRT boost (16 Gy in 8 fractions), sequentially after whole-breast radiotherapy, between 2014 and 2019 were retrospectively identified from a prospectively maintained institutional database. Whole-breast irradiation was delivered after IORT using either conventional or moderately hypofractionated schedules according to institutional practice. The primary endpoint was ipsilateral breast tumour recurrence (IBTR). Secondary endpoints included nodal recurrence, distant metastasis, overall survival (OS), and breast cancer-specific survival (BCSS). Time-to-event outcomes were estimated using the Kaplan-Meier method, whereas treatment comparisons were performed using Cox proportional hazards regression with robust sandwich variance estimates clustered by matched pair.
Results: Following 1:1 matching, 400 patients (200 per group) were included. After a median follow-up of 58 months, the cumulative incidence of local recurrence was 3.5% and 2.0%, respectively, with no statistically significant difference between treatment groups (HR 1.80, 95% CI 0.58–5.58; p = 0.312). Likewise, no significant differences were observed for nodal recurrence-free survival (HR 0.98, 95% CI 0.19–5.16; p = 0.980), distant metastasis-free survival (HR 0.92, 95% CI 0.38–2.23; p = 0.859), breast cancer-specific survival (HR 0.79, 95% CI 0.30–2.10; p = 0.634), or overall survival (HR 1.19, 95% CI 0.59–2.40; p = 0.636).
Conclusions: In this matched-pair analysis, an intraoperative low-energy X‑ray boost achieved oncologic outcomes comparable to those of a conventional postoperative EBRT boost in patients undergoing breast-conserving therapy for high-risk early breast cancer. These findings support IORT boost as an effective and well-tolerated alternative that may simplify treatment delivery without compromising long-term oncologic outcomes.
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BibTeX
@article{sarria2026intraoperative,
title = {{Intraoperative or postoperative radiotherapy boost in high-risk breast cancer: a matched-pair analysis}},
author = {Gustavo R. Sarria and Cas Dejonckheere and Jorge Fernandez and Jose Burgos and Adela Heredia and Eleni Gkika and Gustavo J. Sarria and Paola Fuentes-Rivera},
journal = {Strahlentherapie Und Onkologie},
year = {2026},
month = sep,
doi = {10.1007/s00066-026-02592-3},
url = {https://doi.org/10.1007/s00066-026-02592-3},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Intraoperative or postoperative radiotherapy boost in high-risk breast cancer: a matched-pair analysis
AU - Gustavo R. Sarria
AU - Cas Dejonckheere
AU - Jorge Fernandez
AU - Jose Burgos
AU - Adela Heredia
AU - Eleni Gkika
AU - Gustavo J. Sarria
AU - Paola Fuentes-Rivera
PY - 2026
DA - 2026/09/17
JO - Strahlentherapie Und Onkologie
DO - 10.1007/s00066-026-02592-3
UR - https://doi.org/10.1007/s00066-026-02592-3
AB - Purpose: The optimal boost technique following breast-conserving surgery for patients with high-risk early breast cancer remains controversial. This study compared oncologic outcomes following an intraoperative radiotherapy (IORT) boost using low-energy X‑rays with those of a conventional external beam radiotherapy (EBRT) boost in a matched-pair cohort. Methods: Patients treated with breast-conserving surgery followed by either an upfront IORT boost (20 Gy prescribed to the applicator surface) or a postoperative EBRT boost (16 Gy in 8 fractions), sequentially after whole-breast radiotherapy, between 2014 and 2019 were retrospectively identified from a prospectively maintained institutional database. Whole-breast irradiation was delivered after IORT using either conventional or moderately hypofractionated schedules according to institutional practice. The primary endpoint was ipsilateral breast tumour recurrence (IBTR). Secondary endpoints included nodal recurrence, distant metastasis, overall survival (OS), and breast cancer-specific survival (BCSS). Time-to-event outcomes were estimated using the Kaplan-Meier method, whereas treatment comparisons were performed using Cox proportional hazards regression with robust sandwich variance estimates clustered by matched pair. Results: Following 1:1 matching, 400 patients (200 per group) were included. After a median follow-up of 58 months, the cumulative incidence of local recurrence was 3.5% and 2.0%, respectively, with no statistically significant difference between treatment groups (HR 1.80, 95% CI 0.58–5.58; p = 0.312). Likewise, no significant differences were observed for nodal recurrence-free survival (HR 0.98, 95% CI 0.19–5.16; p = 0.980), distant metastasis-free survival (HR 0.92, 95% CI 0.38–2.23; p = 0.859), breast cancer-specific survival (HR 0.79, 95% CI 0.30–2.10; p = 0.634), or overall survival (HR 1.19, 95% CI 0.59–2.40; p = 0.636). Conclusions: In this matched-pair analysis, an intraoperative low-energy X‑ray boost achieved oncologic outcomes comparable to those of a conventional postoperative EBRT boost in patients undergoing breast-conserving therapy for high-risk early breast cancer. These findings support IORT boost as an effective and well-tolerated alternative that may simplify treatment delivery without compromising long-term oncologic outcomes.
SN - 0179-7158
SN - 1439-099X
ER -