Cancer-related fatigue has a multidimensional nature and complaints typically increase during adjuvant treatment for breast cancer. Physical exercise might prevent or reduce cancer-related fatigue. So far, no meta-analysis has investigated the effects of physical exercise on different dimensions of fatigue. The aim of the present meta-analysis was to investigate the effects of physical exercise during adjuvant breast cancer treatment on physical and psychosocial dimensions of fatigue. We performed a systematic literature search in PubMed, Embase and the Cochrane Library in June 2015. Randomised controlled trials reporting the effects of physical exercise during adjuvant breast cancer treatment on different dimensions of fatigue were included. Pooled effects of 6 exercise programmes (including 784 patients) showed significant beneficial exercise effects on general fatigue (ES: -0.22, 95% CI -0.38; -0.05) and physical fatigue (ES: -0.35, 95% CI -0.49; -0.21). Effects on fatigue subscales 'reduced activity' (ES: -0.22, 95% CI -0.38; -0.05) and 'reduced motivation' (ES: -0.18, 95% CI -0.35; -0.01) were also in favour of physical exercise. No effects were found on cognitive and affective fatigue. Including only the supervised exercise programmes (n=4 studies), slightly larger pooled effect estimates were found on general fatigue (ES: -0.25, 95% CI -0.47; -0.04) and physical fatigue (-0.39, 95% CI -0.56; -0.23). In conclusion, physical exercise during adjuvant breast cancer treatment has beneficial effects on general fatigue, physical fatigue, 'reduced activity' and 'reduced motivation', but did not show effects on cognitive and affective fatigue. Largest effect sizes are found for physical fatigue, suggesting that this is the fatigue dimension most sensitive to physical exercise.
Keywords: Breast cancer; Chemotherapy; Fatigue; Meta-analysis; Physical exercise.
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