Cardiac health in breast cancer (CHiB): protocol for a single-centre, randomised controlled trial

The incidence of breast cancer has increased from 900 000 to 2.3 million new annual cases over the last 25 years. The 5-year survival rate has markedly risen to over 90% worldwide due to significant therapeutic advancements. Longer survival in patients with breast cancer means more patients may experience long-term effects of their treatments, including cancer therapy-related cardiac dysfunction (CTRCD). To date, there is no established primary prevention to minimise CTRCD. The Cardiac Health in Breast Cancer study is a two-arm, single-centre, randomised controlled trial investigating the impact of an exercise programme on cardiac changes in patients with breast cancer undergoing cardiotoxic cancer therapy. 48 females with breast cancer will be randomised to either a 12-month intervention group (IG) or a control group (CG). The IG will receive a combination of supervised high-intensity interval training (HIIT) and high-intensity resistance training (HIRT) for 6 months, while the CG will follow WHO guidelines for physical activity independently. All participants will undergo transthoracic echocardiography, cardiac magnetic resonance (CMR) imaging and cardiopulmonary exercise testing at baseline, after 6 months and after 12 months. The primary endpoint is the occurrence of symptomatic or asymptomatic CTRCD at the time points of examination, detected by cardiac imaging, which may be mitigated by structured physical exercise. Secondary endpoints include assessments of cardiac inflammation as detected by CMR, mitochondrial dysfunction, health-related quality of life, the occurrence of fatigue, depression and anxiety, as well as exercise capacity, average heart rate, heart rate variability and daily physical activity.