Exercise interventions on health-related quality of life for cancer survivors

Abstract

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. To evaluate the effectiveness of exercise on overall HRQoL and HRQoL domains among adult post-treatment cancer survivors. 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. 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. 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. 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. 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.