Exercise Benefits Cancer Patients During and After Treatment

Roxanne Nelson

August 20, 2012

August 20, 2012 — Exercise can improve quality of life for patients both during and after the end of active treatment, according to 2 reviews published online August 15 in the Cochrane Database of Systematic Reviews.

Both found that exercise has a beneficial effect on a number of health-related quality of life (HRQoL) domains, including cancer-specific concerns, body image/self-esteem, emotional wellbeing, sexuality, sleep disturbance, and social functioning.

Exercising during and after the exercise program was also found to be effective in reducing anxiety, fatigue, and pain.

"Together, these reviews suggest that exercise may provide quality-of-life benefits for people who are undergoing or who have undergone treatment for cancer," said Shiraz I. Mishra, MBBS, PhD, lead author of both reviews and associate director of the Prevention Research Center at the University of New Mexico in Albuquerque.

"However, we need to treat these findings with caution because the trials we included looked at many different kinds of exercise programs, which varied by type of exercise, length of the program, and how hard the participants had to exercise," explained Dr. Mishra in a statement. "We need to understand from future trials how to maintain the positive impacts of exercise in the longer term and whether there are particular types of exercise that are suited to particular types of cancer."

Plethora of Evidence

A growing body of evidence suggests that exercise helps improve survival, prevent declines in fitness, improve outcomes (e.g., reduce fatigue and emotional distress), and reduce the risk for certain cancers.

In one study of patients with nonmetastatic disease (55.6% had prostate cancer and 32.5% had breast cancer), participating in an aerobic exercise program was significantly associated with less fatigue and more vigor.

A recent literature review found that physical activity is associated with improved survival in people with breast and colon cancer. The strongest evidence was seen for breast cancer survivors, with "fairly consistent evidence" from observational studies that physical activity either before or after a breast cancer diagnosis is associated with a reduction in both breast-cancer-specific and all-cause mortality. The risk reduction was statistically significant, ranging from 41% to 51% in nearly half the studies.

The next strongest evidence was for colorectal cancer, with statistically significant reduced risks for colorectal-cancer-specific mortality ranging from 45% to 61% in several studies.

In an editorial accompanying that study, Edward L. Giovannucci, MD, ScD, from the Department of Nutrition at the Harvard School of Public Health, Boston, Massachusetts, explained that "many treatments may increase survival, but at a cost of quality of life; physical activity may not only extend life but may also enhance its quality."

Adequate physical activity should be a standard part of cancer care.

"Even though direct effects of physical activity on cancer are not definitely proven, given that physical activity is generally safe, improves quality of life for cancer patients, and has numerous other health benefits, adequate physical activity should be a standard part of cancer care," he noted.

Other recent studies have found that vigorous physical activity appears to offer protection against prostate cancer progression because of its effects on DNA repair and cell-cycle pathways, that about 150 minutes of moderate to vigorous activity can reduce the risk for endometrial cancer, and that exercise even provides benefits for patients with advanced lung cancer.

Improvement Noted Across Domains

The first review involved 56 trials, in which 2286 participants were randomized to an exercise group and 1985 were randomized to a comparison group. Of these trials, 36 involved patients who were undergoing active treatment for their disease, 10 looked at patients during and after treatment, and 10 involved patients who were scheduled for active treatment.

The type of exercise evaluated varied in the 56 studies, and included walking (by itself or in combination with cycling, resistance training, or strength training), resistance training, strength training, cycling, yoga, and Qigong.

"The results suggest that exercise interventions compared with control interventions have a positive impact on overall HRQoL and certain HRQoL domains," write the authors.

When looking at subgroups, breast cancer survivors had a significantly greater reduction in anxiety than patients with other types of cancer. For survivors with other types of cancer, but not breast cancer, there was a greater reduction in depression, fatigue, and sleep disturbances, and a greater improvement in HRQoL, emotional wellbeing, physical functioning, and role function.

In addition, moderate and vigorous exercise improved HRQoL and physical functioning, and reduced in anxiety, fatigue, and sleep disturbances better than mild exercise.

Cautious Interpretation

The authors warn that these results need to be "interpreted cautiously" because of the heterogeneity of exercise programs and the measures used to assess HRQoL and HRQoL domains, and the risk for bias in many trials.

"Further research is required to investigate how to sustain positive effects of exercise over time and to determine essential attributes of exercise (mode, intensity, frequency, duration, timing) by cancer type and cancer treatment for optimal effects on HRQoL and its domains," they conclude.

Similar Benefits Observed

The second review involved 40 trials, in which 1927 participants were randomized to an exercise group and 1764 were randomized to a comparison group.

Of these trials, 30 involved patients who had completed treatment for primary or recurrent cancer and 10 trials looked at patients both during and after completing cancer treatment. Exercise interventions included strength training, resistance training, walking, cycling, yoga, Qigong, and tai chi. A wide variety of measures were used for HRQoL and its domains.

In this review, the authors could not draw any conclusions about the effects of exercise interventions on the HRQoL domains of cognitive function, physical functioning, general health perspective, role function, and spirituality.

As with the first review, the authors advise caution when interpreting the results because of heterogeneity and risk for bias.

The first study was funded by the National Institute for Health Research Health Technology Assessment Programme, UK; and HTA Project 10/81/01. The second study was funded by Cancer Restitution Funds to the State of Maryland; the National Institute for Health Research Health Technology Assessment Programme, UK; and HTA Project 10/81/01. The authors have disclosed no relevant financial relationships.

Cochrane Database Syst Rev. 2012;8:CD008465, CD007566. Abstract, Abstract

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