McNeely, M. L., Campbell, K. L., Rowe, B. H., Klassen, T. P., Mackey, J. R., & Courneya, K. S. (2006). Effects of exercise on breast cancer patients and survivors: a systematic review and meta-analysis. Canadian Medical Association Journal, 175, 34–41.

Databases seached were MEDLINE, CINAHL, EMBASE, PsycINFO, CANCERLIT, Cochrane Library, PEDro, and SPORTDiscus through March 2005.

Fourteen randomized trials were included. Nonrandomized trials, pilot studies, and studies reported only in abstract form were excluded. Therapeutic exercise regimens addressing only specific impairments to shoulder and arm were not included. Studies with an additional treatment arm or combined intervention (e.g., exercise with diet modification) were included only if the effects of exercise could be isolated. Studies were required to have quality of life, cardiorespiratory fitness, or physical functioning as a primary outcome. Secondary outcomes of interest included symptoms of fatigue, body composition, and adverse events resulting from the exercise intervention. Methodologic quality of each included study was evaluated using eight quality criteria specified a priori.

Outcomes were quality of life, cardiorespiratory fitness, physical functioning, symptoms of fatigue, body composition, and adverse events resulting from the exercise intervention.

There was wide variability in the exercise interventions evaluated. Interventions included Tai Chi Chuan, aerobic exercise (walking, cycle ergometer, and arm ergometer), resistance training (weights and resistance bands), and mixed aerobic and resistance exercise. Exercise programs were of moderate or low intensity, and the interventions included a mixture of supervised and self-directed programs, delivered individually or in groups. Overall, study reports provided too little detail concerning the frequency, intensity, time, and type of exercise to allow for determination for an exercise dose-response. Similarly, limited detail about the adherence to the exercise program was provided, and few studies had been designed to include monitoring of activity in the comparison group, so that potential contamination could be gauged.

• A total of 717 participants were included, with sample sizes for individual studies ranging from 16 to 123 participants.
• Participants in the included studies were women with early to later stage (stage 0–III) breast cancer or who had undergone breast cancer surgery with or without adjuvant cancer therapy.
• Clinical heterogeneity in treatment (e.g., chemotherapy, radiation therapy, and hormonal therapy) was evident, particularly in trials of exercise during adjuvant treatment for breast cancer.

Six studies involving 319 patients assessed the effect of exercise on symptoms of fatigue. Although all of the studies showed improvements in symptoms of fatigue with exercise, only two reported statistically significant improvements. These two studies were also the only studies performed following breast cancer treatment. The pooled results from all six studies showed that exercise significantly improved symptoms of fatigue (standardized mean difference [SMD] = 0.46; 95% confidence interval [CI] [0.23, 0.70]). The pooled results from the four studies performed during adjuvant cancer treatment showed a nonsignificant effect on fatigue (SMD = 0.28; 95% CI [-0.02, 0.57]). Four studies reported adverse events; in one study, two of 23 participants reported that participation in the home-based exercise program (self-monitored walking program) resulted in worsening of fatigue.

• Of the 14 studies included in this review, the median score for methodologic quality was 3 (range 0–8). Only four of the 14 studies were considered high quality.
• The most common methodologic shortcomings included failure or inadequate blinding of outcome assessor and inadequate participant concealment of study group allocation.