Abstract
Background
Cancer survivors experience numerous disease and treatment-related adverse outcomes and poorer health-related quality of life (HRQoL). Exercise interventions are hypothesized to alleviate these adverse outcomes. HRQoL and its domains are important measures for cancer survivorship.
Objectives
To evaluate the effectiveness of exercise on overall HRQoL and HRQoL domains among adult post-treatment cancer survivors.
Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, MEDLINE, EMBASE, CINAHL, PsycINFO, PEDRO, LILACS, SIGLE, SportDiscus, OTSeeker, and Sociological Abstracts from inception to October 2011 with no language or date restrictions. We also searched citations through Web of Science and Scopus, PubMed’s related article feature, and several websites. We reviewed reference lists of included trials and other reviews in the field.
Selection criteria
We included all randomized controlled trials (RCTs) and controlled clinical trials (CCTs) comparing exercise interventions with usual care or other nonexercise intervention to assess overall HRQoL or at least one HRQoL domain in adults. Included trials tested exercise interventions that were initiated after completion of active cancer treatment. We excluded trials including people who were terminally ill, or receiving hospice care, or both, and where the majority of trial participants were undergoing active treatment for either the primary or recurrent cancer.
Data collection and analysis
Five paired review authors independently extracted information on characteristics of included trials, data on effects of the intervention, and assessed risk of bias based on predefined criteria. Where possible, meta-analyses results were performed for HRQoL and HRQoL domains for the reported difference between baseline values and follow-up values using standardized mean differences (SMD) and a random-effects model by length of follow-up. We also reported the SMDs between mean follow-up values of exercise and control group. Because investigators used many different HRQoL and HRQoL domain instruments and often more than one for the same domain, we selected the more commonly used instrument to include in the SMD meta-analyses. We also report the mean difference for each type of instrument separately.
Main results
We included 40 trials with 3694 participants randomized to an exercise (n = 1927) or comparison (n = 1764) group. Cancer diagnoses in study participants included breast, colorectal, head and neck, lymphoma, and other. Thirty trials were conducted among participants who had completed active treatment for their primary or recurrent cancer and 10 trials included participants both during and post cancer treatment. Mode of the exercise intervention included strength training, resistance training, walking, cycling, yoga, Qigong, or Tai Chi. HRQoL and its domains were measured using a wide range of measures.
The results suggested that exercise compared with control has a positive impact on HRQoL and certain HRQoL domains. Exercise resulted in improvement in: global HRQoL at 12 weeks’ (SMD 0.48; 95% confidence interval (CI) 0.16 to 0.81) and 6 months’ (0.46; 95% CI 0.09 to 0.84) follow-up, breast cancer concerns between 12 weeks’ and 6 months’ follow-up (SMD 0.99; 95% CI 0.41 to 1.57), body image/self-esteem when assessed using the Rosenberg Self-Esteem scale at 12 weeks (MD 4.50; 95% CI 3.40 to 5.60) and between 12 weeks’ and 6 months’ (mean difference (MD) 2.70; 95% CI 0.73 to 4.67) follow-up, emotional well-being at 12 weeks’ follow-up (SMD 0.33; 95% CI 0.05 to 0.61), sexuality at 6 months’ follow-up (SMD 0.40; 95% CI 0.11 to 0.68), sleep disturbance when comparing follow-up values by comparison group at 12 weeks’ follow-up (SMD -0.46; 95% CI -0.72 to -0.20), and social functioning at 12 weeks’ (SMD 0.45; 95% CI 0.02 to 0.87) and 6 months’ (SMD 0.49; 95% CI 0.11 to 0.87) follow-up.
Further, exercise interventions resulted in decreased anxiety at 12 weeks’ follow-up (SMD -0.26; 95% CI -0.07 to -0.44), fatigue at 12 weeks’ (SMD -0.82; 95% CI -1.50 to -0.14) and between 12 weeks’ and 6 months’ (SMD -0.42; 95% CI -0.02 to -0.83) follow-up, and pain at 12 weeks’ follow-up (SMD -0.29; 95% CI -0.55 to -0.04) when comparing follow-up values by comparison group.
Positive trends and impact of exercise intervention existed for depression and body image (when analyzing combined instruments); however, because few studies measured these outcomes the robustness of findings is uncertain.
No conclusions can be drawn regarding the effects of exercise interventions on HRQoL domains of cognitive function, physical functioning, general health perspective, role function, and spirituality.
Results of the review need to be interpreted cautiously owing to the risk of bias. All the trials reviewed were at high risk for performance bias. In addition, the majority of trials were at high risk for detection, attrition, and selection bias.
Authors’ conclusions
This systematic review indicates that exercise may have beneficial effects on HRQoL and certain HRQoL domains including cancer-specific concerns (e.g. breast cancer), body image/self-esteem, emotional well-being, sexuality, sleep disturbance, social functioning, anxiety, fatigue, and pain at varying follow-up periods. The positive results must be interpreted cautiously due to the heterogeneity of exercise programs tested and measures used to assess HRQoL and HRQoL domains, and the risk of bias in many trials. Further research is required to investigate how to sustain positive effects of exercise over time and to determine essential attributes of exercise (mode, intensity, frequency, duration, timing) by cancer type and cancer treatment for optimal effects on HRQoL and its domains.
Plain language summary
Can exercise interventions enhance health-related quality of life among cancer survivors?
Cancer survivors often have many psychological and physical adverse events as a result of the cancer and treatment for it. They also suffer from poorer quality of life (QoL) than people without cancer. Some studies have suggested that exercise may be helpful in reducing negative outcomes and improving the QoL of people who have finished cancer treatment. Also, a better QoL may predict longer life. This review looked at the effect of exercise on QoL and areas of life that make up QoL (e.g. tiredness, anxiety, emotional health) among people who had finished all cancer treatment.
The review included 40 trials with a total of 3694 people. The results suggest that exercise may improve overall QoL right after the exercise program is completed. Exercise may also reduce the person’s worry about his or her cancer, and affect the way the person views his or her body. Exercise may also help the way the person deals with emotions, sexuality, sleep problems, or functions in society. Exercise also reduced anxiety, tiredness, and pain at different times during and after the exercise program. No effect of exercise was found on the person’s ability to think clearly or his or her role function in society. Also, no effect of exercise was found on the way the person views his or her spiritual or physical health, or physical ability.
However, these findings need to be viewed with caution because this review looked at many different kinds of exercise programs, which varied by type of exercise, length of the program, and how hard the trial participants had to exercise. Also, the investigators used a number of different ways to measure QoL.
More research is needed to see how to maintain the effects of exercise over a longer period of time after the exercise program is completed, and to determine which parts of the exercise program are necessary (i.e. when to start the program, type of exercise, length of program or exercise session, how hard to exercise). It is also important to find out if one type of exercise is better for a specific cancer type than another for the maximum effect on QoL.
