ASTRO 2020: Risk of Radiation-Induced Heart Disease in Patients Treated for Breast Cancer
Posted: Thursday, November 19, 2020
The main cause of non–cancer-related mortality in breast cancer is radiation-induced heart disease. A phase III study, conducted by Dan Ou, MD, of Ruijin Hospital at the Shanghai Jiaotong University School of Medicine, and colleagues, analyzed how cardiac toxicity is managed in patients with breast cancer treated with multidisciplinary therapy. These researchers presented these findings during the 2020 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 2080), indicating those with cardiovascular risk factors may be more vulnerable to radiation-induced heart disease.
The study's eligible participants ranged from 18 to 70 years old and had a baseline left ventricular ejection fraction of greater than 50% before radiotherapy. A total of 233 patients were recruited, and each received adjuvant chemotherapy of either taxanes or anthracycline. Patients were then randomly assigned to groups categorized by dose-volume histogram constraints for the heart as Dmean ≤ 6 Gy, V30 ≤ 20%, V10 ≤ 50%, or control. Every 3 months up until 1 year, cardiac toxicity at the baseline before radiotherapy was evaluated.
A total of 143 participants completed their 1-year follow up, leaving 77 and 66 patients in the study and control groups, respectively. In the experimental group, the Dmean of the heart was found to be 374.9 ± 205.3 cGy; in the control group, a similar result of 376.7 ± 204.7 cGy was obtained. Subclinical cardiac events occurred in 29 patients in each group, yet no clinical cardiac toxicity was observed. In general, the heart rate increased after CT yet decreased after radiotherapy. There was no significant decrease in left ventricular ejection fraction during follow-ups, whereas the diastolic function index increased after radiotherapy. The investigators found notable correlations between pro–B-type natriuretic peptide increase and heart V10 at the 6-month mark, creatine kinase (CK)-MB increase and V10 at 3 months, and CK-MB and Dmean also at 3 months.
Disclosure: The study authors reported no conflicts of interest.
