Exercise may cut breast cancer risk up to 30%
Women who exercise during reproductive or postmenopausal years experience the greatest cancer risk reduction, a study says. Even moderate activity can make a difference.
By Christine S. Moyer, amednews staff. Posted July 10, 2012.
Physicians should encourage all women
to be physically active, regardless of how much they weigh. That’s
because exercise, particularly during the reproductive and
postmenopausal years, might help lower breast cancer risk, says the lead
author of a study on the topic.
Women who engaged in 10 to 19 hours of physical activity per week
during their reproductive years or after menopause experienced a 30%
reduced risk of developing breast cancer, according to a study published
online June 25 in Cancer. Exercise also lowered cancer risk among overweight women who had a body mass index of 25 to 29.9 (ncbi.nlm.nih.gov/pubmed/22733561/) .
Physical activity did not reduce the likelihood of developing breast
cancer in obese women who had a BMI of 30 or higher. But being active
did make their risk similar to that of women of normal weight who do not
exercise, said lead study author Lauren E. McCullough, MSPH.
“The intensity of physical activity doesn’t need to be strenuous to
receive health benefits,” said McCullough, a doctoral candidate in the
Dept. of Cancer Epidemiology at the University of North Carolina
Gillings School of Global Public Health. During their reproductive or
postmenopausal years, women “can walk or do things that are considered
moderate and get the same health benefits” as people who exercise
vigorously, she said.
Researchers examined data on 1,504 women 20 to 98 who were newly
diagnosed with breast cancer between Aug. 1, 1996, and July 31, 1997.
The women were matched to a control group of 1,555 similarly aged
females who had no history of breast cancer. Both groups were part of
the Long Island Breast Cancer Study Project.
During that study, participants reported all recreational physical
activity they participated in for at least one hour per week during
three months. Such activity was defined as leisure-time exercise, which
could include gardening, team sports, running and walking, McCullough
said.
Researchers in the Cancer study found a 6% lower risk of
developing breast cancer among premenopausal and postmenopausal women
who reported ever engaging in recreational physical activity compared
with females who never exercised.
A more significant finding was that women who exercised during their
reproductive years or after menopause experienced the greatest reduction
in breast cancer risk, McCullough said. A possible reason is that the
high level of hormonal changes during those life stages might boost the
benefits of physical activity, she said.
Weight gain after menopause, even among highly active women, however,
seems to reduce or eliminate the benefits of exercise, the study said.
Breast cancer is the second-most common cancer among women after
non-melanoma skin cancer, according to the Centers for Disease Control
and Prevention. In 2008, there were 210,203 U.S. women diagnosed with
breast cancer, and 40,589 females died of the disease, according to the
CDC’s most recent data.
2012 American Medical Association
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