CBCT-Guided Online Adaptive Ultrahypofractionated Whole-Breast Radiotherapy for Early-Stage Breast Cancer: Dosimetric Outcomes and Acute Toxicity.
4 affiliations
- 1Specialty Hospital Radiochirurgia Zagreb, 10431 Sveta Nedelja, Croatia.
- 2Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia.
- 3Medical Faculty Osijek, University Josip Juraj Strossmayer in Osijek, 31000 Osijek, Croatia.
- 4Medical Faculty, Juraj Dobrila University of Pula, 52100 Pula, Croatia.
Abstract
Ultrahypofractionated whole-breast radiotherapy reduces treatment burden but increases the importance of accurate dose delivery at each fraction. This retrospective single-center study evaluated cone-beam computed tomography-guided online adaptive radiotherapy in 55 patients with early-stage breast cancer treated with 26 or 27 Gy in five fractions. Dosimetric analysis was available for 52 patients and 259 paired scheduled and adapted fractions. Linear mixed-effects models with a patient-specific random intercept were used to account for repeated fractions within individual patients. The adapted plan was selected for 242 out of 260 delivered fractions (93.1%). Mean planning target volume V95% increased from 93.52 ± 2.94% with the scheduled plan to 98.13 ± 1.04% with adaptation (p < 0.001), with reduced interfraction variability. Ipsilateral lung V30% increased modestly from 13.94% to 14.96% (p < 0.001). In left-sided cases, no significant differences were observed for heart V25% (1.400% vs. 1.395%; p = 0.3825) or left anterior descending coronary artery D0.03 cm³ (1.771 vs. 1.873 Gy; p = 0.1390). Acute grade 1 toxicity occurred in five patients (9.1%), with no grade ≥ 2 events. Mean treatment-session duration was 28 min. Online adaptation significantly improved daily target coverage and was technically feasible within a five-fraction whole-breast workflow. Acute toxicity was limited in this cohort, while longer follow-up and cumulative dose analyses are needed to further define its impact on organ-at-risk exposure and clinical outcomes.
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BibTeX
@article{ursi2026cbctguided,
title = {{CBCT-Guided Online Adaptive Ultrahypofractionated Whole-Breast Radiotherapy for Early-Stage Breast Cancer: Dosimetric Outcomes and Acute Toxicity.}},
author = {Giovanni Ursi and Matea Lekić and Hrvoje Kaučić and Aleksandar Kovačević and Domagoj Kosmina and Karla Schwarz and Dragan Schwarz and Damir Vučinić},
journal = {Current oncology (Toronto, Ont.)},
year = {2026},
month = oct,
doi = {10.3390/curroncol33100634},
url = {https://europepmc.org/article/MED/42930201},
note = {CC BY},
}
RIS
TY - JOUR
TI - CBCT-Guided Online Adaptive Ultrahypofractionated Whole-Breast Radiotherapy for Early-Stage Breast Cancer: Dosimetric Outcomes and Acute Toxicity.
AU - Giovanni Ursi
AU - Matea Lekić
AU - Hrvoje Kaučić
AU - Aleksandar Kovačević
AU - Domagoj Kosmina
AU - Karla Schwarz
AU - Dragan Schwarz
AU - Damir Vučinić
PY - 2026
DA - 2026/10/20
JO - Current oncology (Toronto, Ont.)
DO - 10.3390/curroncol33100634
UR - https://europepmc.org/article/MED/42930201
AB - Ultrahypofractionated whole-breast radiotherapy reduces treatment burden but increases the importance of accurate dose delivery at each fraction. This retrospective single-center study evaluated cone-beam computed tomography-guided online adaptive radiotherapy in 55 patients with early-stage breast cancer treated with 26 or 27 Gy in five fractions. Dosimetric analysis was available for 52 patients and 259 paired scheduled and adapted fractions. Linear mixed-effects models with a patient-specific random intercept were used to account for repeated fractions within individual patients. The adapted plan was selected for 242 out of 260 delivered fractions (93.1%). Mean planning target volume V95% increased from 93.52 ± 2.94% with the scheduled plan to 98.13 ± 1.04% with adaptation (p < 0.001), with reduced interfraction variability. Ipsilateral lung V30% increased modestly from 13.94% to 14.96% (p < 0.001). In left-sided cases, no significant differences were observed for heart V25% (1.400% vs. 1.395%; p = 0.3825) or left anterior descending coronary artery D0.03 cm³ (1.771 vs. 1.873 Gy; p = 0.1390). Acute grade 1 toxicity occurred in five patients (9.1%), with no grade ≥ 2 events. Mean treatment-session duration was 28 min. Online adaptation significantly improved daily target coverage and was technically feasible within a five-fraction whole-breast workflow. Acute toxicity was limited in this cohort, while longer follow-up and cumulative dose analyses are needed to further define its impact on organ-at-risk exposure and clinical outcomes.
SN - 1198-0052
SN - 1718-7729
ER -