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Exercise can reduce breast cancer risk
[Posted: Mon 25/06/2012 by Gillian Tsoi www.irishhealth.com]
Exercise, even mild physical activity, can reduce the risk of breast cancer, according to experts in the US.
They found that doing either mild or intense exercise, before or after the menopause, may cut the risk of the common disease.
However, weight gain may undo these benefits.
While studies have shown that physical activity reduces breast cancer risk, many questions remain.
For example, how often, how long, and how intense does physical activity have to be to provide benefits? Also, do women with all body types experience a reduced risk when they exercise, and does exercise reduce the risk of all types of breast cancer?
Researchers at the University of North Carolina Gillings School of Global Public Health looked for a link between recreational physical activity, done at different time points in life, and the risk of developing breast cancer.
They studied over 1,500 women with breast cancer and over 1,500 women without breast cancer. All women were between 20-98 years old.
Women who exercised either during their reproductive or postmenopausal years had a reduced risk of developing breast cancer. Women who exercised 10- 19 hours per week experienced the greatest benefit with an approximate 30% reduced risk.
A decreased risk of breast cancer were seen at all levels of intensity, and exercise seemed to preferentially reduce the risk of hormone receptor positive breast cancer (ER or PR positive), which is the most commonly diagnosed tumor type among American women.
"The observation of a reduced risk of breast cancer for women who engaged in exercise after menopause is particularly encouraging given the late age of onset for breast cancer," said Lauren McCullough, who led the study.
When the researchers looked at the joint effects of physical activity, weight gain, and body size, they found that even active women who gained a significant amount of weight - particularly after menopause - had an increased risk of developing breast cancer.
This indicates that weight gain can eliminate the beneficial effects of exercise on breast cancer risk, they said.
The study was conducted as part of the Long Island Breast Cancer Study Project, an investigation of possible environmental causes of breast cancer.
The study was published online in CANCER, a peer-reviewed journal of the American Cancer Society.
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