In a recent systematic review published in BMC Cancer, researchers summarize previous data on the effects of exercise on cancer fatigue.
Cancer-related fatigue (CRF) affects many cancer patients who either are undergoing or have undergone treatment. This condition occurs when patients are physically, mentally, or emotionally tired due to cancer therapies. Cancer fatigue can have wide-ranging adverse effects on many aspects of patient health and well-being. There are national guidelines that recommend physical activity to treat cancer fatigue without the use of drugs, but the evidence to support these recommendations is ambiguous and previous systematic reviews in this area have reported varied results. Hence, an American group recently conducted a systematic review of past systematic reviews and published the findings in BMC Cancer, to gain a broader perspective on previous research conducted on the relationship between exercise and cancer-related fatigue.
This meta-analysis examined previous systematic reviews of randomized controlled trials, which specifically compared exercise as a treatment versus no intervention in adult cancer patients. The authors removed studies if they included other interventions that were not of interest such as nutrition intervention, included youth, or did not report the appropriate outcome. They also evaluated the quality of each systematic review using a standardized questionnaire.
The authors narrowed down a wide search on systematic reviews on exercise as a treatment for cancer fatigue to 16 reviews, which were conducted in the Netherlands, China, Columbia, United States, France, and Germany. These reviews comprised of an average of 12 studies and included a total of 1,220 participants. These studies span different types of cancer at different stages of progression and treatment. To measure cancer fatigue, the studies used reporting instruments such as the Piper Fatigue and the Functional Assessment of Cancer Therapy scales.
The authors observed substantial variation in the effect of exercise on cancer fatigue, but all of the results from the 16 systematic reviews show either a direction towards benefit or a significant benefit in cancer fatigue. This suggests that exercise may have some benefit on cancer fatigue, albeit not a strong or consistent one among all participants. The vast scope of this study minimizes the bias towards certain types of cancers or patients from certain countries.
This review adds to the evidence that exercise can be useful in reducing the effects of cancer fatigue but requires more substantial and stronger evidence to provide better guidelines. Some mechanisms of exercise on health are known, such as decreased inflammation and improved brain and nervous system function. Additional parameters of study participants could be studied, however, to obtain a broader view of the field, which will, in turn, be able to guide medical practices and decision-making for doctors who treat patients with cancer fatigue.
Written by Branson Chen, BHSc
Reference: Kelley GA, Kelley KS. Exercise and cancer-related fatigue in adults: a systematic review of previous systematic reviews with meta-analyses. BMC cancer. 2017 Oct 23;17(1):693.