Exercise improves cancer survival, reduces cancer risk, scientists say

03/26/04

Research demonstrates even moderate physical activity is a significant factor in diminishing the risk or increasing the likelihood of survival for certain cancers in women

ORLANDO Regular exercise, long associated with better cardiovascular health, muscle tone and weight control, also may help prevent certain cancers and improve the odds of cancer survival. Two studies report a strong correlation between such ordinary activities as walking or performing household chores and reduced risk of endometrial and breast cancers, and between walking and improved rates of breast cancer survival. Another demonstrates that moderate exercise decreased the levels of a blood marker that predicts lower survival from several types of cancer among high-risk, obese individuals. The research was presented here today at the 95th Annual Meeting of the American Association for Cancer Research.

Physical activity and endometrial cancer risk: Abstract No. 3712

Regular exercise, as well as routine activities such as walking and household chores, may reduce a woman's risk of endometrial cancer by as much as 30 to 40 percent, according to researchers from the Vanderbilt University Medical Center in Nashville and the Shanghai Cancer Institute in China.

Charles E. Matthews, Ph.D., of Vanderbilt, and his colleagues, evaluated 832 women with endometrial cancer, aged 30 to 69 years, identified through the Shanghai Cancer Registry. The control population, matched according to age, was randomly selected from female residents of Shanghai. The women were asked about the amount of walking and cycling for transportation, intentional exercise and household activity in which they engaged as adolescents age 13 to 19 years and as adults. Lifetime occupational activity was also evaluated. Women who reported exercise participation in both adolescence and adulthood were 30 to 40 percent less likely to develop endometrial cancer than women who reported no exercise in either life-period. Common activities, including household chores and daily walking, were also found to reduce risk by about 30 percent. Reductions in risk were evident for women who reported walking for 60 minutes each day compared to women reporting less than 30 minutes of walking per day; likewise for women who reported four or more hours per day of household activity, compared to women reporting two hours or less each day. Engaging in higher levels of overall physical activity appeared to minimize some of the adverse effects of body weight on endometrial cancer risk. Neither cycling nor occupational activity appeared to influence endometrial cancer risk in this study.

"In recent years, we have accumulated strong evidence that an active lifestyle can reduce the risk of colon and breast cancer; now we are finding that physical activity may also reduce risk of endometrial cancer" said Matthews, the lead author of this report.

"We were particularly pleased to see the beneficial effect on endometrial cancer risk of more accessible and lower intensity forms of activity like walking for transportation and doing household chores, as well as intentional exercise," he added. "Our results support the idea that the risk of cancer can be reduced by maintaining an active lifestyle."

Physical activity and survival after breast cancer diagnosis: Abstract No. 1462

Researchers from Brigham and Women's Hospital and Harvard University tested the hypothesis that physical activity increases survival rates among women with breast cancer.

"We already knew that exercise improves the quality of life after a breast cancer diagnosis," said lead investigator Michelle D. Holmes, M.D., Dr.P.H., "but little is known about how physical activity affects survival."

Holmes and her team drew on participants in the Nurses' Health Study, reviewing data on women with stages I, II, and III breast cancer, diagnosed between 1984 and 1996. In that study, leisure-time physical activity is measured in metabolic equivalent task hours per week (met-hours/week one met is the energy expenditure and caloric requirement at rest. One hour of walking represents three met-hours of physical activity.) The researchers looked specifically at exercise beginning two years after diagnosis, in order to avoid inclusion of women undergoing treatment. The cohort of 2,296 women were followed from 1986 until either their death from breast cancer or June 2002, whichever came first.

Taking into account the stage of disease, obesity and other factors, the relative risk of death from breast cancer was decreased with every level of physical activity compared with being sedentary. The risk of death from breast cancer was 19 percent less among women who undertook 3-8.9 met-hours/week of exercise; 54 percent less for 9-14.9 met-hours/week; 42 percent less for 15-23.9 met-hours/week; and 29 percent less for 24 or more met-hours/week of recreational exercise.

"We were able to show that even a moderate amount of physical activity improved the odds of surviving breast cancer," Holmes said. "It is especially heartening for women recovering from breast cancer to know that the benefit is as readily accessible as walking for 30 minutes on most days of the week."

Effect of a yearlong exercise intervention on markers of inflammatory response among postmenopausal women: Abstract No. 5496

Another approach to the association between exercise and cancer survival and prevention was presented here today by researchers from the Fred Hutchinson Cancer Research Center in Seattle, led by Cornelia M. Ulrich, PhD. C-reactive protein (CRP) and serum amyloid A (SAA) are signals for inflammation that have been associated with cancer risk and survival. Knowing that these biomarkers often are elevated among the overweight, the team investigated the effects of a moderately intense, yearlong exercise program on CRP and SAA.

The study population consisted of 114 postmenopausal, overweight (body mass index greater than 24) and sedentary women, ages 50 to 75. About half of these performed moderate physical activity 45 minutes per day, five days a week, for one year, while the other half participated in weekly stretching exercises. The concentrations of CRP and SAA in their blood were measured at the beginning and the end of the test period.

"Among obese women, those with a body mass index of 30 or higher," Ulrich reported, "concentrations of CRP declined steadily over the course of the year from a baseline of 0.40 milligrams per deciliter to 0.32 milligrams. This effect of exercise on inflammatory markers may help to explain in part the associations observed between increased physical activity and reduced risk for cancer and other chronic disease."

Source: Eurekalert & others

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