A systematic review 1 http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16818906 used the following sources for literature search: Cochrane Central Register of Controlled Trials, Medline, Embase, Cinahl, PsychINFO, CancerLit, PEDro, SportDiscus and grey literature, until March 2005. Two independent reviewers performed the search. In total, 140 papers were identified, of which 25 were thoroughly analyzed by two researchers. 14 studies involving 717 participants were included in the final review. The included studies fulfilled the following criteria: RCT design; comparison of exercise with a placebo, controlled comparison or standard care; the effects of exercise could be isolated from other treatment effects; participants were women with early to later stage (Stage O-III) breast cancer or who had undergone breast cancer surgery with or without adjuvant cancer therapy; and the primary outcomes were quality of life, cardiorespiratory fitness or physical functioning. Secondary outcomes of interest included symptoms of fatigue and body composition. Two reviewers assessed the quality of each study using a list of eight criteria. The median quality score was 3 on a scale of 1 to 8. Four trials were considered high quality. Study heterogeneity was statistically tested. In the absence of heterogeneity, the results of a study were pooled with the results of respective other studies for statistical analyses. Effect sizes with 95% confidence intervals (CIs) were calculated. For dichotomous variables, odds ratios (ORs) with 95% CIs were calculated. Very different exercise programs were used in the different studies.
Three studies involving 194 patients compared exercise with usual care. Exercise led to significant improvements in quality of life and was superior to usual care in respect of this outcome. The change was also considered clinically significant. Exercise significantly improved cardiorespiratory fitness as measured with different methods in all the 9 studies (473 patients) that reported this outcome. Three studies (95 patients) used direct measurement of peak oxygen consumption and it was statistically significantly improved with exercise, on average by nearly one metabolic unit (MET). Body mass index was not significantly altered. Physical functioning and physical well-being components of quality of life measurements scales were significantly improved (4 studies, 208 patients, SMD 0.84, 95% CI 0.36 to 1.32).
Six studies (319 patients) assessed the effect of exercise on symptoms of fatigue. All of the studies showed improvements in symptoms of fatigue with exercise and the pooled results were statistically significant (SMD 0.46, 95% CI 0.23 to 0.70). When analyzed separately, however, the change was significant in only 2 studies that were carried out after finished cancer treatment.
Adverse events from exercise programs were reported in only 4 studies (163 patients). One study (66 patients) reported 8 injuries to the back, 3 to the upper extremities and 5 to the ankle during one year of exercise. In another study (23 patients), one shoulder tendinitis and two cases of a worsening of fatigue were reported during the 7-week exercise. There was no statistically significant difference in the occurrence of lymphedema between exercise and control interventions. All in all, the safety of exercise programmes directed to cancer patients could not be thoroughly assessed because adverse events were reported in only a few studies.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes).
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