Structured exercise does not show consistent cardioprotective effects on LVEF in patients with breast cancerExercise Does Not Show Clear Heart Benefits for Breast Cancer Patients

PURPOSE: To evaluate whether structured exercise, compared with usual care, preserves left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), and cardiac biomarkers in women with breast cancer receiving anthracyclines and/or anti-HER2 therapy. METHODS: We performed a systematic review and meta-analysis of randomized controlled trials. Risk of bias was assessed with the revised Cochrane risk-of-bias tool for randomized trials (RoB 2), and certainty of evidence with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. When clinically and methodologically comparable, effects were pooled as net differences in change (ΔEG - ΔCG) using random-effects models. The primary synthesis was restricted to the baseline-to-end-of-anthracycline-treatment window (~ 4 months). RESULTS: Seven trials (9 reports; n = 513) were included. Most trials had some concerns or high risk of bias. Quantitative synthesis was feasible in only two trials. No between-group differences were observed for LVEF (MD 0.07, 95% CI - 1.38 to 1.52; I = 28.2%) or GLS (MD - 0.10, 95% CI - 0.79 to 0.58; I = 0%). Confidence intervals were wide and compatible with benefit, no effect, or harm. Biomarker data were too heterogeneous for meta-analysis. Comparative clinical cardiovascular-event and survival outcomes and formal assessments of heart failure with preserved ejection fraction (HFpEF) were not reported. CONCLUSION: Current randomized evidence is sparse, heterogeneous, and of low certainty. Available data do not confirm a consistent cardioprotective effect of exercise on LVEF or GLS and do not permit conclusions about clinical cardiovascular events, survival, or HFpEF.