The Cardiac Effects of Radiotherapy on Women with Breast Cancer Based on Laterality

Background:
Recent advances in the early detection and management of breast cancer have conferred longer patient survival. Breast irradiation-induced cardiotoxicity has been associated with a decrease in the echocardiographic markers of myocardial function and an increase in cardiac mortality.
Objectives:
This study aimed to determine the cardiac effects of radiotherapy on patients with breast cancer based on cancer laterality.
Methods:
The present study assessed the records of 72 consecutive women with breast cancer who were referred to the Cardio-Oncology Department of Rajaie Cardiovascular Medical and Research Center between April 2017 and September 2020 and had baseline echocardiographic examinations and at least one follow-up echocardiographic examination within the first year of the initial examination. The patients were divided into left- and right-sided breast cancer groups to compare the results. The two groups were compared regarding the means of 2D Left Ventricular Ejection Fraction (LVEF), 3D LVEF, Global Longitudinal Strain (GLS), and Global Circumferential Strain (GCS) before and after radiotherapy. Analysis of Covariance (one-way ANCOVA) was used to compare the results (alpha = 0.05). All analyses were carried out using the SPSS software, version 26.
Results:
The changes in the means of 2D LVEF, 3D LVEF, GLS, and GCS were statistically significant among all the patients irrespective of cancer laterality (P < 0.001, P < 0.001, P = 0.001, and P = 0.002, respectively). However, no significant differences were observed between the left- and right-sided breast cancer groups vis-à-vis the means of 2D LVEF, 3D LVEF, GLS, and GCS (P = 0.44, P = 0.65, P = 0.21, and P = 0.25, respectively).
Conclusions:
The study results showed significant declines in the means of 2D LVEF, 3D LVEF, GLS, and GCS following radiotherapy. The patients with right-sided breast cancer exhibited a significant decrease in all the mentioned measures, whereas those with left-sided breast cancer showed no significant decline in post-radiotherapy speckle-tracking parameters. In addition, comparison of the patients with left- and right-sided breast cancers revealed no significant difference in the echocardiographic parameters of cardiotoxicity regarding cancer laterality.