Exercise Improves Quality of Life, Longevity for Cancer Patients
When you are healthy, exercise can help to keep you that way. However, even when you are ill, such as with a disease like cancer, exercise has positive benefits such as improving several factors involved in quality of life and longevity after diagnosis. Two studies out this month add to the body of knowledge we currently have to encourage daily physical activity.
For the first review, investigators with the University of Hong Kong analyzed the findings of 34 human trials that evaluated how exercise affects adults with cancer. Each trial consisted of an average of 93 participants who had been diagnosed with prostate, breast, lung, colorectal, gynecological, or gastric cancer. The average age of the patients was 55 years. The forms of exercise included in the trial were resistance, strength, and aerobic training with a median duration of 13 weeks.
Physiologically, factors that improved with exercise included BMI (body mass index) and body weight, blood sugar control, oxygen consumption, walking distance, lower limb strength and handgrip strength. Psychologically, patients had less depression and fatigue, and an enhanced quality of life.
One especially positive finding was the reduction in insulin-like growth factor-1 (IGF-1), a protein that appears to stimulate the growth of certain cancer cells, particularly of the breast and prostate.
Different types and levels of exercise had specific effects. For example, breast cancer patients found that aerobic exercise plus resistance was much more effective on physical fitness, emotional fitness, overall well-being and fears about breast cancer than aerobic activity alone.
Judy Ho MD concludes that in cancer survivors that have completed their main course of treatment, "Quality of life was a clear significant benefit of physical activity and that clinically, there were important positive effects on physical functions and quality of life."
In a separate study, scientists with the University of California, San Francisco (UCSF) have identified almost 200 genes whose expression in the prostate gland is linked to vigorous exercise. The finding may help explain how physical activity improves survival from the disease.
Last year, two studies by UCSF and Harvard School of Public Health showed that brisk walking or vigorous exercise such as jogging for three or more hours a week was linked to a lowered risk of prostate cancer progression and death after diagnosis. Delving deeper into explaining why, senior study author June Chan ScD analyzed the expression of a total of 20,000 genes in 70 men with low-grade prostate cancer. This information was correlated with the mens’ self-report on their exercise patterns.
Over 100 genes were “up-regulated” or more active among the men who regularly exercised and 75 were “down-regulated” or less active. Among those that exhibited a greater expression were some that are thought to thwart cancer progression as well as genes involved in cell cycle and DNA repair. Unfortunately, though, only vigorous exercise was associated with the positive benefits. Less intense, less frequent activity had little impact on gene expression said Chan.
"Vigorous physical activity may provide clinical benefits for men diagnosed with earlier stage prostate cancer," Dr. Chan concludes. "The finding suggests some interesting leads on mechanisms by which physical activity may protect against prostate cancer progression." Further research on these genes may help to determine how exercise contributes to improved cancer survivorship, and suggest novel strategies for prevention, she adds.
Fong DYT, et al "Physical activity for cancer survivors: Meta-analysis of randomized controlled trials" BMJ 2012; DOI: 10.1136/bmj.e70.
Bourke L, et al "Physical activity for cancer survivors" BMJ 2012; DOI: 10.1136/bmj.d7998.
Magbanua MJM, et al "Physical activity and prostate gene expression in men with low-risk prostate cancer" GUCS2012; Abstract 189.
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