Aerobic exercise can help relieve fatigue related to breast and prostate cancer, both during and after treatment, according to an updated review published online November 14 in the Cochrane Database of Systematic Reviews.
The findings suggest that aerobic exercise should "be considered as one component of a management strategy for fatigue that may include a range of other interventions and education," write review authors Fiona Cramp, PhD, and James Byron-Daniel, PhD, from the University of West England in Bristol, United Kingdom.
In the past, cancer patients were often encouraged to rest to manage their fatigue. Currently, this approach is considered counterproductive because "inactivity leads to muscle wasting and loss of cardiorespiratory fitness, leading to increased fatigue," the authors write.
This review, which involved 56 studies and 4068 patients, builds on a previous review from the same researchers (Cochrane Database Syst Rev. 2008;2:CD006145) by differentiating the specific effects of aerobic training from other forms of exercise, and points to benefits in breast and prostate but not hematologic malignancies.
"Further work is necessary to determine the most effective parameters of exercise for fatigue management, including multimodal exercise (combined aerobic and resistance), frequency and duration of each exercise session, and intensity of exercise," Drs. Cramp and Byron-Daniel write.
"It remains to be determined whether the type of cancer treatment alters the beneficial effects of exercise on cancer-related fatigue," they note. Future research should examine a broader range of cancer diagnoses, "including patients with advanced disease and those receiving palliative care," they add.
Effects of Exercise on Cancer Fatigue
Although 2 complementary reviews have examined the role of drugs (Cochrane Database Syst Rev. 2010;7:CD006704) and psychosocial interventions (Cochrane Database Syst Rev. 2009;1:CD006953) in modifying cancer-related fatigue, "there is currently no definitive stand on exercise for cancer-related fatigue from the American College of Sports Medicine, with minimal detail given on exercise prescription in those that do recommend it," they note.
The updated review involved 28 studies from the original review and 28 from an updated literature search, which provided data on 1461 patients who received an exercise intervention and 1187 control subjects.
Although the participants had various cancer diagnoses, many were from studies of breast cancer.
The exercise interventions occurred both during and after cancer treatment. The duration of the intervention ranged from 3 weeks to 1 year, and involved aerobic activity, resistance training, or flexibility exercises.
Delivery of the intervention varied widely, from home-based to supervised programs, and intensity varied from self-pacing to regimens that involved the monitoring of heart rate and oxygen uptake.
There was also a wide variation in the frequency and duration of exercise interventions. Some sessions were conducted daily and some just 2 times per week; some sessions lasted 10 minutes and others lasted 120 minutes.
For the outcome of fatigue, which was assessed using a wide range of outcome measures across studies, aerobic exercise such as walking and cycling had a statistically significant benefit over no exercise (P = .03).
The results of the review should not be considered in isolation, the authors note. A range of nonpharmacologic interventions can also be considered beneficial, they point out. "Interventions that may be delivered in conjunction with an exercise program include, but are not limited to, psychosocial therapies, stress management, nutrition therapy, and sleep therapy."
Update of Current Understanding
This review updates current understanding in this field, specifically pertaining to cancer trajectory, type of exercise, and particular cancers, said Margaret McNeely, PhD, an expert in cancer rehabilitation and exercise in an email to Medscape Medical News.
"The findings support exercise to help reduce symptoms of fatigue in survivors of the 2 most common forms of cancer: breast cancer and prostate cancer," noted Dr. McNeely, who is assistant professor in the Department of Physical Therapy at the University of Alberta and in the Department of Oncology and the Rehabilitation Medicine Department at the Cross Cancer Institute in Edmonton, Canada.
"Although benefits were found only in the studies examining breast and prostate cancers, it is important to note that few studies have been performed with other cancer groups. Moreover, at this point in time, less is known about the benefits of other types of exercise, such as weight training (resistance exercise) and yoga. These types of activities appear to show promise but need formal evaluation," she explained.
Dr. McNeely emphasized that even when cancer patients cannot formally "exercise" during treatment, it is still important to stay as active as possible. "Exercising during cancer treatment is easier said than done, especially when symptoms such as fatigue become problematic.... Staying active will help to prevent losses in muscular strength and overall fitness and, as demonstrated in this review, reduce fatigue."
She added that patients returning to more vigorous exercise after cancer treatment might "benefit from seeing an exercise specialist who can help them begin exercising at a level that is appropriate for their stage of cancer recovery and overall health status."
The research was funded by the National Institute for Health Research Health Technology Assessment program in the United Kingdom. Dr. Cramp, Dr. Byron-Daniel, and Dr. McNeely have disclosed no relevant financial relationships.
Cochrane Database Syst Rev. 2012;11:CD006145. Abstract
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