Effects of exercise on breast cancer patients and survivors: a systematic review and meta-analysis
Margaret L. McNeely,
Kristin L. Campbell,
Brian H. Rowe,
Terry P. Klassen,
John R. Mackey and
Kerry S. Courneya
From the Department of Behavioural Medicine, Faculty of Physical
Education, University of Alberta (McNeely, Campbell, Courneya), the
Department of Emergency Medicine, University of Alberta and Capital
Health (Rowe), the Department of Paediatrics, Stollery Children's
Hospital and University of Alberta (Klassen) and the Department of
Medical Oncology, Cross Cancer Institute and University of Alberta
(Mackey), Edmonton, Alta.
Physical exercise has been identified as a
potentialintervention to improve quality of life in women with
breastcancer. We sought to summarize the available evidence
concerningthe effects of exercise on breast cancer patients and
We searched the Cochrane Central Register of
ControlledTrials, MEDLINE, EMBASE, CINAHL, PsychINFO, CancerLit,
PEDroand SportDiscus as well as conference proceedings, clinical
practice guidelines and other unpublished literature resources.We
included only randomized controlled trials that examined exercise
interventions for breast cancer patients or survivors with quality of
life, cardiorespiratory fitness or physica lfunctioning as primary
outcomes. We also extracted data on symptoms of fatigue, body
composition and adverse effects.
Of 136 studies identified, 14 met all the
inclusioncriteria. Despite significant heterogeneity and relatively
smallsamples, the point estimates in terms of the benefits of
exercisefor all outcomes were positive even when statistical
significancewas not achieved. Exercise led to statistically significan
timprovements in quality of life as assessed by the Functional
Assessment of Cancer Therapy–General (weighted mean difference[WMD]
4.58, 95% confidence interval [CI] 0.35 to 8.80) and Functional
Assessment of Cancer Therapy–Breast (WMD 6.62, 95% CI1.21 to 12.03).
Exercise also led to significant improvements in physical functioning
and peak oxygen consumption and in reducing symptoms of fatigue.
Interpretation: Exercise is
an effective intervention to improve quality of life, cardiorespiratory
fitness, physical functioning and fatigue in breast cancer patients and
survivors. Larger trials that have a greater focus on study quality and
adverse effects and that examine the long-term benefits of exercise are
needed for this patient group.
Is exercise effective in reducing the risk of breast cancer in postmenopausal women
McTiernan A, Kooperberg C, White E, Wilcox S, Coates R, Adams-Campbell LL, et al.
Recreational physical activity and the risk of breast cancer in postmenopausal women: the Women’s Health Initiative Cohort Study. JAMA 2003;290:1331-6.
Reports have shown that excess weight and large sizes have been associated to a higher risk of breast cancer. It remains unclear the amount or intensity of exercise that is needed to produce this effect and at what age the physical activity must occur. The study consisted of a group of 74,171 women aged 50-79 from 40 U.S. clinical centers between 1993-1998 for the Women’s Health Initiative Observational Study.
Information collected was based on factors such as medical, family history, physical activity, diet, height, weight and lifetime use of hormone therapy.
In a four-and-a-half year follow-up of the study, breast cancer was newly diagnosed in 1,780 of the women. The study also revealed that women who participated in regular strenuous physical activities at the age of 35 decreased their risk of breast cancer by 14 percent compared with less active women.
This is further evidence that exercise before and after menopause are linked to breast cancer prevention. The effect was realized even with small increments of exercise equivalent to one to two hours per week of brisk walking. The results have shared similarities to those associated with decreasing the risk of cardiovascular disease among postmenopausal women and those with diabetes.