Effects of tailored exercise prescription on cardiorespiratory fitness in breast cancer survivors: findings from the munich cardio-oncology-exercise retrospective registry

Background Breast cancer patients (BC) and survivors (BCS) are at higher risk of cardiovascular disease-related morbidity. Reduced cardiorespiratory fitness (CRF), measured by peak oxygen consumption (VO2peak) is a key prognostic marker in BC and BCS. Low CRF, defined as relative VO2peak ≤ 18 mL/kg/min and/ or predicted VO2peak ≤ 85 %, impairs functional independence. Purpose To investigate whether tailored exercise prescription leads to an improvement of VO2peak in BC and BCS with reduced CRF during or short-term after predominantly (anthracycline based) chemotherapy. Methods This retrospective analysis included 25 female BC and BCS (stages I-III without visceral metastases) from the Munich Cardio-Oncology-Exercise retrospective Registry with limited CRF. All participants underwent cardiopulmonary exercise testing during or shortly after completion of chemotherapy and received tailored exercise recommendations at baseline for non-supervised training. Physical activity was assessed via a structured telephone interview and quantified in metabolic equivalents (METs) per minute per week. The primary outcome was a change in VO2peak from baseline to follow-up. A significance level of α = 0.05 was determined a priori. Results A total of 25 female BC and BCS (mean age of 58.4 ± 13.4 years) were included. Mean physical activity comprised 1754.1 ± 1236.6 MET minutes per week. Significant improvement in VO2peak was observed after a mean follow-up of 48.2 months, with large interindividual variations (mean 2.8 ± 4.5 mL/kg/min, p = 0.005). Additionally, Circulatory Power (CP, product of peak oxygen uptake and peak systolic blood pressure) significantly increased (mean 713.5 ± 1062.8 mmHg· mL/kg/min, p = 0.003), while the ratio of systolic blood pressure to oxygen consumption (SBP/VO2 slope) significantly decreased (mean – 1.02 ± 1.7 mmHg/mL/kg/min, p = 0.009), supporting improvement in CRF. Conclusion CRF can be significantly improved in BC and BCS with impaired CRF following tailored exercise prescription and non-supervised training during or shortly after completion of chemotherapy. As the effects of exercise training on VO2peak are less pronounced in BCS compared to apparently healthy individuals, tailored exercise prescription is of utmost importance in this high-risk population to re-gain functional independence.