Exercise and cancer rehabilitation: A systematic review

Summary

Introduction

Cancer is increasingly being viewed as a chronic illness requiring long-term management, and there is a growing need for evidence-based rehabilitation interventions for cancer survivors. Previous reviews have evaluated the benefits of exercise interventions for patients undergoing cancer treatment and long-term survivors, but none have investigated the role of exercise during cancer rehabilitation, the period immediately following cancer treatment completion. This systematic review summarises the literature on the health effects of exercise during cancer rehabilitation and evaluates the methodological rigour of studies in this area to date.

Methods

Relevant studies were identified through a systematic search of PubMed and Embase to April 2009. Data on study design, recruitment strategy, participants, exercise intervention, adherence rates, and outcomes were extracted. Methodological rigour was assessed using a structured rating system.

Results

Ten studies were included. Breast cancer patients were the predominate patient group represented. Most interventions were aerobic or resistance-training exercise programmes, and exercise type, frequency, duration and intensity varied across studies. Improvements in physical functioning, strength, physical activity levels, quality of life, fatigue, immune function, haemoglobin concentrations, potential markers of recurrence, and body composition were reported. However, all studies were limited by incomplete reporting and methodological limitations.

Conclusions

Although the methodological limitations of studies in this new field must be acknowledged, initial evidence indicates that exercise is feasible and may provide physiological and psychological benefits for cancer survivors during the rehabilitation period. Future studies with rigorous study designs are now required to advance the field.

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.