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Exercise is an effective way to improve or recover heart health in adults with cancer, according to researchers.

A meta-analysis of 48 randomized controlled trials with more than 3,500 adult cancer patients showed that exercise therapy doubled peak oxygen consumption (VO_2peak; in mL O₂ × kg^-1 × min^-1) compared with no exercise (weighted mean differences +2.13 mL O₂ × kg^-1 × min^-1; P<0.001).

Exercise therapy was associated with a 2.80 mL increase in VO_2peak compared with no change (+0.02 mL) in controls, reported Jessica M. Scott, PhD, of Memorial Sloan Kettering Cancer Center in New York City, and colleagues in the .

In 30 trials that directly measured VO_2peak, there were 44 adverse events, consisting mostly of dizziness and chest and muscle-related pain; myocardial infarction and hip fracture were also reported. The mean standard deviations in loss to follow-up, attendance, and adherence rates were 11%, 84%, and 88%, respectively.

"Collectively, these findings support the of exercise therapy to prevent and/or mitigate cancer treatment-associated reductions in VO_2peak or to recover impaired VO_2peak in the post-treatment setting," Scott's group wrote.

Strategies to improve or recover cardiorespiratory fitness in patients with adult-onset cancer "are of major clinical importance," the study authors emphasized, noting that up to 80% have significant impairment in peak oxygen consumption. Studies suggest that this is associated with risk factors for cardiovascular disease, poor quality of life, and fatigue, and an increased risk of all-cause mortality, including death from cancer.

Many of the studies in the meta-analysis were limited by inadequate monitoring and reporting for adherence to treatment, which "could lead to erroneous conclusions about the harm-to-benefit ratio of exercise therapy in a given indication," the researchers said.

Most of the trials assessed programs consisting of 30 to 45 minutes of exercise done three times a week, and support national for cancer survivors recommending "avoidance of inactivity." However, the overall findings of the current review and meta-analysis may not extend to physical activity issued by the American College of Sports Medicine, Scott and colleagues pointed out. "Elucidation of the appropriate dose, timing, and length of exercise therapy as well as whether improvements in [cardiorespiratory fitness] correspond with hard clinical end points, are major research priorities in this field."

Asked for his perspective, Steven A. Grover, MD, director of the McGill Comprehensive Health Improvement Program (CHIP) at Montreal General Hospital in Quebec, who was not involved in the study, told 番茄社区, "Yes, this meta-analysis proves that cancer patients will improve cardiac fitness with an exercise program."

Grover, who is also at McGill University, noted that some of the studies included in the meta-analysis "go far beyond building aerobic capacity, showing that exercise can help dispel chronic fatigue, reduce depressive episodes, and lower blood pressure, blood sugar, and blood lipid levels."

Treating a patient for cancer is only half the battle, he said: "The first thing is to realize this problem exists." Once the patient is in remission, "circle back and find out what the patient's life looks like. If you discover that the patient is sedentary, you've got a chance to get them back on their feet and restore them to full health."

show that more than 30% of young women with breast cancer get no exercise at all up to 10 years after treatment, he pointed out. "Not only do they not recover their physical fitness, but they don't recover psychologically or emotionally either. It's like post-traumatic stress disorder."

Still, creating an exercise program that empowers cancer patients without endangering their health can be challenging, admitted Grover, who is leading a joint web-based research project between McGill, the University of Montreal, and St. Mary's Hospital. The 8- to 12-week Physical Activity Challenge will assess the impact of working out before, during, and after treatment in 50 patients with breast cancer. Among other options, patients can choose to exercise from home with a supportive buddy, or join a small virtual team of other cancer survivors.

Some sort of accountability is important, Grover added: "Social connectivity is a big part of the story too." The program, designed with input from cancer survivors, has already been shown to increase physical activity among hospital workers, medical students, physicians, and enlisted military personnel, relieving stress, improving sleep, and reducing fatigue in the process, he said.

Study Details

For the meta-analysis, Scott et al used the Cochrane Central Register of Controlled Trials, Embase, PubMed, and the Cumulative Index to Nursing and Allied Health Literature from inception to October 2016. A total of 23 of the 48 trials (48%) were published between 2001 and 2014, with the rest published in 2015 or after.

Overall, 3,632 patients with a mean age of 55 were included: 1,990 (55%) who received adjuvant exercise therapy; and 1,642 (45%) who received only usual care. A total of 68% were female, and 21 of the studies (44%) were conducted in breast cancer patients.

Twenty-seven trials (56%) included an exercise intervention of 12 weeks or less, and 31 (65%) provided participants with a supervised location.

Notably, an exercise prescription with a nonlinear dosing schedule that progressively increased exercise intensity while leaving time for rest and recovery, was more effective for improving VO_2peak than standard scheduling, the analysis showed.

"Collectively, these findings create the provocative notion that approaches that individualize therapy intensity on the basis of specific physiologic thresholds together with continual progression of exercise dose ... may optimize VO_2peak improvements," the researchers wrote. "Nevertheless, such a notion is speculative at present, given the small number of trials that have investigated this prescription approach in cancer and other clinical populations."

Limitations of the current study, the team said, include the use of subgroup analyses to identify treatment-response modifiers, which did not take into account the individual response to exercise therapy.

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