Objective: This study, derived from the phase 3 SAFE trial (ClinicalTrials.gov identifier: NCT2236806), explores subclinical cardiac damage in breast cancer patients receiving anthracycline-based chemotherapy and left-sided breast radiation therapy (RT).
Materials and methods: Eligible patients were randomized to a cardioprotective pharmacological therapy (bisoprolol, ramipril, or both) or placebo, with cardiac surveillance at multiple time-point using standard and 3-dimensional echocardiography. Dosimetric parameters were analysed, including mean heart dose (MHD) and various metrics for heart substructures, employing advanced contouring techniques and auto-contouring software.
Results: In the analysis of left-sided breast RT patients, the study encompassed 39 out of 46 irradiated individuals, focusing on GLS and 3D-LVEF outcomes with ≥ 10% worsening, defined as subclinical heart damage. Distinct RT schedules were used, with placebo exhibiting the highest ≥ 10% worsening (36.4%). In terms of treatment arms, bisoprolol exhibited 11.1% worsening, while ramipril 16.7% and bisoprolol + ramipril 25%. For patients with no subclinical damage, the mean MHD was 1.5 Gy; for patients with subclinical heart damage, the mean MHD was 1.6 Gy (p = 0.94). Dosimetric parameters related to heart and heart substructures (left anterior descending artery, right and left atrium, right and left ventricle) showed no statistically significant differences between patients with and without subclinical damage.
Conclusion: Our results emphasize the crucial role of cardioprotective measures in mitigating adverse effects, highlighting RT as having negligible influence on cardiac performance. An extended follow-up assessment of the whole series is warranted to determine whether a subclinical effect could significantly influence clinical outcomes and cardiac events.
Trial registration: ClinicalTrials.gov NCT02236806.
Keywords: Anthracycline-based chemotherapy; Breast cancer; Cardioprotective therapy; Left-sided breast radiotherapy; Subclinical cardiac damage.
© 2024. Italian Society of Medical Radiology.