Early effect of contemporary radiotherapy protocol on myocardium in patients with breast cancer assessed with cardiac magnetic resonance

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): University Medical Centre Ljubljana Research Grant. Introduction Early cardiotoxicity of modern radiotherapy (RT) is not known. Purpose To study the early cardiotoxic effect of contemporary RT on myocardium with cardiac magnetic resonance (CMR) in patients with breast cancer (BC). Methods Patients with in-situ ductal carcinoma of the breast, scheduled for RT were included. All patients had undergone surgical tumorectomy. Exclusion criteria were prior systemic chemotherapy, prior RT or known cardiac disease. Patients were treated with 3-dimensional conformal RT or intensity-modulated RT, left-sided BC patients were also scheduled for deep inspiration breath hold protocol, if feasible. Patients underwent CMR imaging prior to RT and within 2 weeks after RT. Left and right ventricular volumes and ejection fraction, global native and postcontrast T1 values and T2 values, prior to and after completion of RT were analyzed. All patients provided written informed consent. Results A total of 40 female patients (mean age 55 ± 7 years) were included, 22 with left-sided BC. The mean radiation dose was 42 Gy. CMR results are presented in Table 1. Left-sided BC patients had statistically significant increase in global T2 values. There were no significant differences in other studied parameters. No patient developed pericardial effusion and no patient had presence of late gadolinium enhancement at both exams. Conclusion Modern RT of left-sided BC is associated with increased T2 values, most likely representing myocardial edema, early after completion of RT.