Exercise as part of survivorship care in metastatic breast cancer: protocol for the randomized EMBody trial

Exercise is associated with improved survival, physical functioning, treatment tolerability, and quality of life in early-stage breast cancer. These same endpoints matter in metastatic breast cancer (MBC). Prior trials in MBC have found exercise to be not feasible or of limited benefit, possibly due to inclusion of patients with heterogeneous disease trajectories. Patients with MBC have variable disease trajectories and supportive care needs; those with indolent MBC have longer life expectancy, lower symptom burden and distinct priorities, and are well-positioned to participate in and benefit from an exercise program. The EMBody trial aims to determine the impact of a multimodal exercise intervention on cardiorespiratory fitness, physical function, body composition, and patient-reported outcomes, specifically in patients with stable, indolent MBC. Eligible patients have MBC with no evidence of disease progression on current therapy in the prior 12 months and cannot be receiving cytotoxic chemotherapy. The trial aims to enroll 100 patients, randomized 1:1 to the exercise intervention versus usual care, stratified by baseline function. The virtually-delivered exercise intervention arm achieves moderate intensity exercise with exercise physiologists 3 days/week for 16 weeks. The 60-minute sessions include aerobic, resistance, balance and stretching exercises. The exercise arm receives informational sessions on the role of exercise in cancer and principles of habit and self-efficacy. The primary endpoint is 16 week change in fitness on a ramp treadmill test between the exercise and control arms. Secondary endpoints include change in a physical function, muscle mass assessed by CT scans, and PROs of fatigue and quality of life. Exploratory analysis includes behavioral modifiers of exercise adherence and effectiveness and serologic measures of inflammatory, metabolic, and immune pathway biomarkers. The EMBody trial evaluates exercise in a unique patient population with indolent, non-progressive MBC. Patients living with MBC experience similar symptom burden to those undergoing therapy for early-stage disease and the benefits achieved with exercise could be similarly impactful. This trial will contribute evidence to support expansion of exercise recommendations, among other survivorship care efforts, to those living with metastatic disease. NCT05468034. NCT05468034. Date of registration: 7/12/2022.