ESTRO 2025 - Abstract Book

S526

Clinical - Breast

ESTRO 2025

2376

Poster Discussion Modern radiotherapy for left-sided breast cancer does not influence cardiac biomarkers: A prospective cohort study Preetha Umesh 1 , Kratika Bhatia 1 , Kundan Singh Chufal 1 , Irfan Ahmad 1 , Alexis Andrew Miller 2 , Harsh Vyas 1 , Munish Gairola 1 1 Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi, India. 2 Radiation Oncology, Illawarra Cancer Care Centre, Wollongong, Australia Purpose/Objective: To re-analyze data from our prospective study assessing the association between radiotherapy (RT) and cardiac biomarkers in women with left-sided breast cancer.[1] This re-analysis incorporates additional patients with incomplete data and retrospectively assigns Heart Failure Association of the European Society of Cardiology and the International Cardio-Oncology Society (HFA-ICOS) risk scores to further investigate the relationship between RT and cardiac biomarkers. Material/Methods: Between June 2022 and July 2023, women with left-sided stage I-III breast cancer, without pre-existing coronary heart disease (CHD) or equivalent conditions, and normal baseline echocardiography were enrolled in this study. All patients underwent adjuvant hypofractionated RT and were assessed for cardiac biomarkers (high-sensitivity troponin I (hsTnI), N-terminal pro-brain natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hsCRP)), pre-RT, immediately post-RT, and optionally at 3 months post-RT. The mean heart dose (MHD) was recorded for each patient. Linear mixed modeling (LMM) was employed to assess biomarker changes over time and to evaluate any associations with MHD and HFA-ICOS risk scores. Results: A total of 116 patients were analyzable for hsCRP and NT-proBNP, and 107 patients for hsTnI, with a median follow up of 21.7 months. None of the patients developed major adverse cardiac events (MACE). LMM revealed no significant time-dependent changes in any of the biomarkers measured (hsTnI, NT-proBNP, or hsCRP)(figure 1A). Additionally, no association was found between MHD and changes in biomarker levels (figure 1B). However, increasing age (p = 0.046) and BMI (p = 0.007) were significantly associated with higher NT-proBNP and hsCRP levels, respectively. These results are consistent with prior research showing that age and obesity are independent risk factors for elevated cardiac biomarkers and cardiovascular disease, irrespective of radiation exposure.

Conclusion: Our re-analysis after including additional patients with incomplete data, reinforces our previous findings that cardiac radiation exposure with modern radiotherapy techniques does not influence changes in biomarkers. There were no time-dependent changes in hsTnI, NT-proBNP, and hsCRP levels, with no association with MHD or HFA ICOS risk groups. A search for studies designed to determine cardiovascular changes after breast cancer treatment yielded 34 results, out of which 8 planned to measure serum cardiac biomarkers. Preliminary results from two of these completed studies [BACCARAT (NCT02605512); MEDIRAD EARLY ‐ HEART (NCT03297346)] also indicate no significant change in biomarkers (personal communication). Given our findings and the absence of convincing