GENERAL AND SUPPORTIVE CAREExercise and cancer rehabilitation: A systematic review
Introduction
The population of long-term cancer survivors continues to grow. In 2002 24.6 million people were living with cancer, worldwide.1 Improvements in treatment are, in part, responsible for the increased survival rates and life expectancies for cancer survivors. However, these treatments can be harmful, with many cancer survivors experiencing long-term negative physical and/or psychological effects from their disease or treatment. For this reason cancer is increasingly being viewed as a chronic illness requiring long-term management,2 and the need for evidence-based rehabilitation interventions for this population is growing.
Exercise is increasingly becoming recognised as an important treatment for the recovery and rehabilitation of cancer survivors. The findings from previous reviews and meta-analyses suggest that exercise attenuates a range of physical and psychological complaints after cancer treatment. The benefits are thought to include reductions in fatigue and improvements in immune function, physical functioning, body composition, and quality of life (QoL).3, 4, 5
Courneya and Friedenreich6 were the first to provide a framework for examining the short-term and long-term benefits of exercise after cancer treatment. In their most recent physical activity and cancer control framework, they define the period following initial treatment, and ending with recurrence or death, as survivorship.7 They then separate survivorship into two time periods: the rehabilitation period, which immediately follows primary treatment, and the disease prevention/health promotion period, which describes longer-term survival. The duration of the rehabilitation period is highly variable but continues until any major loss of function is recovered. Courneya and Friedenreich6 suggest that this time period can be defined approximately as the time from treatment completion to 3–6 months post-treatment. They argue that exercise and other types of physical activity are important throughout this period, as well as in the longer term survival period.
Early reviews in this field summarised the evidence from all exercise interventions, regardless of whether patients were in the treatment, rehabilitation or survival period. More recent reviews have separated the results of treatment and post-treatment interventions, but to date, no review has evaluated the effects of interventions offered during the rehabilitation period separately from the effects of those offered during the disease prevention/health promotion period. Therefore, little is known about the specific benefits of exercise immediately following treatment, during which time the goal is to address the acute side-effects of treatment and facilitate a return to pre-treatment health.
In their 2007 summary of the literature on physical activity and cancer control, Courneya and Friedenreich7 identified the rehabilitation period as a key focus for future research, particularly research to examine the feasibility and efficacy of exercise interventions. A number of factors explain this interest in offering exercise programmes during this period. First, during treatment, survivors typically experience a significant decline in their participation in exercise and other physical activities. Their levels of activity may not recover, even years after treatments have been completed.7, 8 Considering the de-conditioned state of cancer survivors and the common presence of acute side-effects at the completion of treatment, the possibilities for improvements in physical functioning, QoL, and immune function during the rehabilitation period are considerable.3 Second, cancer diagnosis has been described as a life changing event and completion of treatment can serve as a motivator to improve lifestyle risk factors, such as exercise and, more generally, physical activity participation. In a recent pilot study of a multi-strategy rehabilitation intervention for colorectal cancer survivors, cancer diagnosis was identified as a motivator for initiating the lifestyle changes promoted in the intervention.9 Participants identified 3–5 months post-treatment as their preferred time to start a rehabilitation programme because they felt that they were fit enough to make behavioural changes at that time, while not yet having lost their motivation to change. In another study, more than half the cancer survivors said they would prefer to begin an exercise programme immediately or soon after treatment, rather than during treatment.7 A potential reason for this preference could be that after treatment the time constraints imposed by medical appointments decrease. The third factor that could explain the interest in offering exercise during the rehabilitation period is the role of exercise programmes in providing continuing support to cancer survivors. Many cancer patients find this period challenging due to a sudden decline in both medical and social support: for example, they often report experiencing unanticipated fear and emptiness.10 Exercise programmes that offer social support to cancer survivors during this period could help them transition from the intense levels of support they receive during treatment.
What is known about the benefits of exercise during the rehabilitation period comes from the first generation of studies to test the efficacy and effectiveness of exercise programmes for cancer survivors in this period. It is now important to identify directions and challenges learned from these studies to prepare the next generation of studies in this field. Therefore, this study reviews the current literature on the role of exercise during the rehabilitation period. The purposes of this narrative systematic review are: (1) to summarise the literature on the health effects of exercise on cancer survivors in the rehabilitation period and (2) to evaluate the methodological rigour of studies that have examined these effects. The review will discuss: recruitment efforts, participants, interventions, adherence and compliance, analysis, and outcomes.
Section snippets
Search strategy and selection criteria
Embase and PubMed were searched for articles prior to and including April 2009. Titles and abstracts were searched using the keywords cancer and exercise and clinical trials. The reference lists of located review articles on the topic and of articles describing original research were also checked. RS and KH developed the search strategy. RS then conducted the initial search, and in consultation with KH, determined eligibility of potential articles. WB confirmed the accuracy of the process used
Results
The database searches identified 668 references. Review of their titles and abstracts revealed that 538 did not meet the inclusion criteria. The full texts of the remaining 130 articles were retrieved for more detailed evaluation. Of these, 117 articles were excluded and 13 were included in this review, based on the study criteria (Fig. 1).
Discussion
This systematic review summarizes the major results and evaluates the methodological quality of exercise interventions for cancer survivors during the rehabilitation period. To our knowledge this is the first review to focus on this time period, which commences immediately after primary cancer treatment is completed. Only 10 studies (described in 13 articles16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28) were located for inclusion in this review, which illustrates the ‘early’ nature of this
Conclusion
Few intervention studies have been conducted with cancer survivors in the rehabilitation period. As might be expected of research in an emerging field, methodological limitations are evident in studies in this field. These make it difficult to draw firm conclusions about the efficacy or effectiveness of exercise interventions for these cancer survivors. Acknowledging these limitations, the initial evidence indicates that exercise programmes are feasible and may provide physiological and
Conflict of interest statement
None of the authors have any financial and personal relationships with other people or organisations that could inappropriately influence this work.
Acknowledgements
RS is supported by a Postgraduate Research Scholarship from The University of Queensland. RS and KH are supported by a NHMRC program grant (Grant No. 301200) in physical activity and health at The University of Queensland, School of Human Movement Studies. Funding sources had no involvement in the study design, data collection, analysis and interpretation of the data, writing of the manuscript, or the decision to submit the manuscript for publication.
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