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Home>Breast Cancer> Active women have better breast cancer survival rates
Active women have better breast cancer survival rates
Women with breast cancer who engaged in an amount of physical activity equivalent to walking 1 or more hours per week had
better survival compared with those who exercised less than that or not at all, according to a study in the May 25 issue of
JAMA.
There is reason to believe that physical activity might extend survival in women with breast cancer, according to background
information in the article. Physical activity has been linked to lower levels of circulating ovarian hormones, which may
explain the relationship between physical activity and breast cancer. Lower estrogen levels among physically active women
with breast cancer could potentially improve survival, although few data exist to support this hypothesis.
Michelle D. Holmes, M.D., Dr.P.H., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues
conducted a study to examine whether higher levels of physical activity after a breast cancer diagnosis would be associated
with longer survival. The study was based on responses from 2,987 female registered nurses in the Nurses' Health Study who
were diagnosed with stage I, II, or III breast cancer between 1984 and 1998 and who were followed up until death or June
2002, whichever came first. Physical activity was measured as metabolic equivalent task (MET) hours. Three MET-hours is
equivalent to walking at average pace of 2 to 2.9 mph for 1 hour.
The researchers found that compared with women who engaged in less than 3 MET-hours per week of physical activity, the
adjusted relative risk of death from breast cancer was 20 percent lower for 3 to 8.9 MET-hours per week; 50 percent lower for
9 to 14.9 MET-hours per week; 44 percent lower for 15 to 23.9 MET-hours per week; and 40 percent lower for 24 or more
MET-hours per week. The benefit of physical activity was particularly apparent among women with hormone-responsive tumors.
The risk of breast cancer death was 50 percent lower for women with hormone-responsive tumors who engaged in 9 or more
MET-hours per week of activity compared with women with hormone-responsive tumors who engaged in less than 9 MET-hours per
week. Compared with women who engaged in less than 3 MET-hours per week of activity, the absolute unadjusted risk of death
reduction was 6 percent at 10 years for women who engaged in 9 or more MET-hours per week.
"It has been estimated that women decrease their levels of physical activity by 2 hours per week after a breast cancer
diagnosis, with greater decreases among obese women, and that less than one third of breast cancer survivors participate in
levels of activity recommended by government agencies. Women with breast cancer who follow the Centers for Disease Control
and Prevention recommendations for all individuals in the United States to exercise at moderate intensity for 30 or more
minutes per day for 5 or more days per week may survive longer," the authors conclude.
(JAMA. 2005;293:2479-2486. Available pre-embargo to the media at http://www.jamamedia.org)
Editor's Note: The research for this article was funded by a grant from the National Institutes of Health.
JAMA and Archives Journals
http://www.jamamedia.org
 
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