Effects of physical exercise after treatment of early breast cancer: systematic review and meta-analysis
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PURPOSE: Randomized clinical trials are inconclusive regarding the role of physical exercise in anthropometric measurements, quality of life, and survival in breast cancer patients. Our aim was to conduct a systematic review and meta-analysis to assess the effects of physical exercise on these outcomes in women who went through curative treatment of early-stage breast cancer. METHODS: Pubmed, Embase, Cochrane Library were searched for randomized clinical trial comparing physical exercise (counseling or structured programs with supervised/individualized exercise sessions) with usual care in women that went through for breast cancer treatment. Primary outcomes were overall survival and disease-free survival, while secondary outcomes were weight loss, body mass index, waist-hip ratio, percentage of body fat, and quality of life. RESULTS: We found 60 randomized clinical trials, only one of them showed mortality data; the HR for mortality was 0.45 (95% CI 0.21-0.97) for the intervention group when compared to the control group. Physical exercise was associated with weight reduction (- 1.36 kg, 95% CI - 2.51 to - 0.21, p = 0.02), lower body mass index (- 0.89 kg/m2, 95% CI - 1.50 to - 0.28, p < 0.01), and lower percentage of body fat (- 1.60 percentage points, 95% CI - 2.31 to - 0.88, p < 0.01). There was an increase in the quality of life (standardized mean difference of 0.45, 95% CI 0.20-0.69, p < 0.01). CONCLUSIONS: The articles found had heterogeneous types of intervention, but they showed significant effects on anthropometric measures and quality of life. Among them, only one study had mortality as outcome and it showed physical exercise as a protective intervention. Despite these findings, publication bias and poor methodological quality were presented. Physical exercise should be advised for breast cancer survivors since it has no adverse effects and can improve anthropometrics measures and quality of life. PROSPERO registry: CRD42014008743.