S210
Clinical - Breast
ESTRO 2026
for Nuclear Safety and Radiation Protection, Paris, France
Patients had a mean age of 65 years (range 52–79). All tumors were ≤ 3 cm, hormone receptor-positive, and of well to moderately differentiated histology (stages pTis-pT2 pN0M0). The mean PTV_Eval represented 19% of the total breast volume. After a median follow- up of 15 months (range 3–26), no local recurrences were reported.Early toxicity was minimal: 65% of patients experienced no toxicity; Grade 1 dermatitis was observed in 10%, Grade 1–2 fatigue in 16%, and Grade 1 pain in 13%. No edema was noted. Late toxicity was also low: 90% of patients had no late effects, while 10% experienced only Grade 1 hyperpigmentation. No radiation-induced fibrosis or telangiectasia was observed.Cosmetic results were favorable, with 97% of patients rated as having an excellent outcome and one patient (3%) rated as good. Conclusion: In conclusion, SBRT-based PBI appears to be a safe, effective, and time-efficient treatment option for selected patients with early-stage breast cancer, showing minimal toxicity and excellent cosmetic results. The high precision of SBRT and the limited irradiated volume likely contribute to these outcomes. References: Meattini I, Marrazzo L, Saieva C, et al. Accelerated Partial-Breast Irradiation Compared With Whole- Breast Irradiation for Early Breast Cancer: Long-Term Results of the Randomized Phase III APBI-IMRT- Florence Trial. J Clin Oncol. 2020 Dec 10;38(35):4175- 4183.T. Major, C. Gutiérrez, B. Guix, E. van Limbergen, V. Strnad, C.Polgár, et al. Recommendations from GEC ESTRO Breast Cancer Working Group (II): Target definition and target delineation for accelerated or boost partial breast irradiation using multicatheter interstitial brachytherapy after breast conserving open cavity surgery. Radiother Oncol. 2016;118:199-204 Keywords: breast cancer, SBRT, radiotherapy Cardiac radiation dose and coronary artery calcification after breast cancer radiotherapy: modifying role of concomitant systemic inflammation Médéa Locquet 1,2 , David Broggio 3 , Jean Ferrières 4 , Jérémy Camilleri 5 , Fabien Milliat 6 , Sophie Jacob 7 1 Biomedical Sciences, Faculty of Medicine, University of Namur, Namur, Belgium. 2 Radiation Epidemiology, Gustave Roussy, Paris, France. 3 PSE-SANTE/SDOS, Authority for Nuclear Safety and Radiation Protection, Paris, France. 4 Department of Cardiology, Rangueil University Hospital, Toulouse, France. 5 Radiation Oncology (Orion), Clinique Pasteur, Toulouse, France. 6 Laboratory of radiobiology of medical exposures, Authority for Nuclear Safety and Radiation Protection, Paris, France. 7 Laboratory of epidemiology, Authority Digital Poster 580
Purpose/Objective: Radiation-induced cardiotoxicity remains a significant concern in breast cancer (BC) patients treated with radiotherapy (RT), with both cardiac radiation exposure and systemic inflammation emerging as key contributors to early cardiovascular complications. This study investigated whether cardiac radiation dose triggers independently or synergistically with systemic inflammation, characterized by C-reactive protein (CRP) elevation, to predict coronary artery calcification (CAC) progression in BC survivors. Material/Methods: We analyzed 101 chemotherapy-naïve BC women who underwent cardiac CT before and 24 months after RT, with dosimetric analysis of left ventricle (LV) radiation exposure. Sustained CRP elevation was defined as increased CRP at both end of RT and 6 months post- RT. Models were run in the overall BC cohort and further stratified by sustained CRP elevation status. Interaction between sustained CRP elevation and LV dose was tested (Wald test). Logistic regressions were also used to estimate the predicted probability of CAC progression for each individual. Predicted probabilities were obtained from the fitted model and used to evaluate the model’s discriminative performance using receiver operating characteristic (ROC) curve analysis. The area under the curves (AUC) with the corresponding 95% confidence interval (CI) was calculated for each model. Results: CAC progression was observed in 28 patients (27.7%). Both sustained CRP elevation (OR=3.42; 95% CI: 1.12– 10.5) and mean LV dose (OR=1.20 per Gy; 95% CI: 1.03–1.40) were independently associated with CAC progression. Although no statistically significant interaction was observed, stratified analyses showed a stronger association between mean LV dose and CAC progression among patients with sustained inflammation (OR=1.39, 95%CI: 1.07-1.81), whereas this association was weaker and non-significant in patients without systemic inflammation (OR=1.12, non-significant). The combined model incorporating both predictors showed improved discriminative performance (AUC=0.733). Conclusion: These findings suggest that systemic inflammation may amplify the effect of cardiac irradiation and that combining inflammatory and dosimetric data improves early prediction of CAC risk. This may help identify high-risk subgroups who could benefit from enhanced cardiovascular monitoring or preventive strategies after BC RT. Keywords: inflammation, c-reactive protein, atherosclerosis
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