The Troponin-I Release in Patients with Left-Sided Early-Stage Breast Cancer Undergoing Adjuvant Whole Breast Radiotherapy: An Iranian Experience

Background: Breast cancer is the most frequent cancer among women. In line with the survival improvement of patients with cancer, the issue of treatment-induced toxicities becomes more important. Objectives: This study aimed at evaluating acute radiation-induced cardiac damage. Methods: Between 2016 and 2019, women with histologically-confirmed early-stage left-sided breast cancer or ductal carcinoma in-situ (DCIS) without prior chemotherapy, who were candidates for adjuvant whole breast radiotherapy, entered the study. The radiation-induced cardiotoxicity was assessed, using a rise in high-sensitivity cardiac troponin I (hscTnI) over the radiotherapy. Likewise, the association between the percentage of heart receiving at least 25Gy (V25Gy) and the rise in hscTnI was evaluated as the secondary endpoint. Results: A total of 22 women were included in this study. Mean ± standard deviation (SD) hscTnI for the whole study population was 12 ± 2 ng/L before and 15 ± 2 ng/L after radiotherapy. The median (interquartile range [IQR]) V25Gy was 8.05% (6.95% - 8.95%). The difference between hscTnI levels before and after radiotherapy was significant (P = 0.001). There was no correlation between V25Gy and the rise in hscTnI (P = 0.18). Conclusions: hscTnI is a sensitive marker to detect early radiation-induced cardiotoxicity. There is no association between V25Gy and the rise in hscTnI over radiotherapy.