Effects of supervised exercise on cancer-related fatigue in breast cancer survivors: a systematic review and meta-analysis

Background: Cancer-related fatigue (CRF) is the most common and distressing symptom in breast cancer survivors. Approximately 40% to 80% of cancer patients undergoing active treatment suffer from CRF. Exercise improves overall quality of life and CRF; however, the specific effects of the training modalities are not well understood. Methods: This study aimed to determine the pooled effects of supervised exercise interventions on CRF in breast cancer survivors. We searched PubMed/MEDLINE, EMBASE, Scopus, CENTRAL and CINAHL databases between December 2013 and January 2014 without language restrictions. Risk of bias and methodological quality were evaluated using the PEDro score. Pooled effects were calculated with a random-effects model according to the DerSimonian and Laird method. Heterogeneity was evaluated with the I-2 test. Results: Nine high-quality studies (n = 1156) were finally included. Supervised aerobic exercise was statistically more effective than conventional care in improving CRF among breast cancer survivors (SMD = -0.51, 95% CI -0.81 to -0.21), with high statistical heterogeneity (P = 0.001; I-2 = 75%). Similar effects were found for resistance training on CRF (SMD = -0.41, 95% CI -0.76 to -0.05; P = 0.02; I-2 = 64%). Meta-regression analysis revealed that exercise volume parameters are closely related with the effect estimates on CRF. Egger's test suggested moderate evidence of publication bias (P = 0.04). Conclusions: Supervised exercise reduces CRF and must be implemented in breast cancer rehabilitation settings. High-volume exercises are safe and effective in improving CRF and overall quality of life in women with breast cancer. Further research is encouraged.