41P - Cancer therapy-related cardiac dysfunction (CTRCD) after radiation therapy for breast cancer: Results of the French BACCARAT study

Background

Radiation therapy (RT) for breast cancer (BC) can result in cardiotoxicity including subtle cardiac dysfunction that can occur early after treatment. In 2022, the first European Society of Cardiology (ESC) guidelines in cardio-oncology defined asymptomatic cancer therapy-related cardiac dysfunction (CTRCD), combining both information on left ventricle ejection fraction (LVEF) and global longitudinal strain (GLS) decrease from baseline. This newly defined event has never been studied in a population of BC patients treated with RT. Objective: To evaluate early to mid-term asymptomatic CTRCD occurrence and to analyze the association with radiation-induced cardiac exposure.

Methods

The BACCARAT study included BC patients treated with RT without chemotherapy, aged 40–75 years. Conventional and 2D Speckle tracking echocardiography was performed before RT and 6 and 24 months after RT. Whole heart, left ventricle (LV), coronary arteries doses, and dose-volume parameters were considered to evaluate the impact of cardiac exposure on CTRCD. Classic cardiac risk factors data were also collected.

Results

The study included 72 BC (of 59 left-sided BC) patients with a mean age of 58 years. A total of 32 (44%) patients developed any grade CTRCD during follow up: 22 (31%) developed early, and 14 (19%) developed midterm dysfunction with or without previous dysfunction only in left BC patients. The doses were generally higher among patients with CTRCD rather than non-CTRCD. Significant dose-response relationships were observed between the risk of CTRCD and cardiac exposure, in particular LV (OR for V2 LV dose =1.03 (1.00-1.06) p=0.01 and circumflex CX artery’s mean dose OR = 2.44 (1.26-4.74) p =0.008, D2 OR = 1.79 (1.13-2.85) p=0.01 and V2 OR = 1.02 (1.01-1.04) p=0.01. The results for the CX artery exposure were robust and significant after adjustment for classic cardiac risk factors and analyses according to the CTRCD grade; however, it did not remain significant for LV.

Conclusions

Our study suggests an association between specific cardiac structures and CTRCD, considering classic cardiac risk factors. However, given the limited number of patients, further research is needed.

Clinical trial identification

NCT02605512.

Editorial acknowledgement

Legal entity responsible for the study

Institut de radioprotection et de sûreté nucléaire (IRSN).

Funding

Société française de cardiologie Électricité de France Société française de cardiologie.

Disclosure

All authors have declared no conflicts of interest.