Physical activity protects against breast cancer
Vigorous exercise can protect women against breast cancer
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Friday, 31, Oct 2008 07:53
Vigorous exercise can protect women against breast cancer, new research claims.
Normal-weight women who exercise are approximately 30 per cent less likely to develop breast cancer than those who don't, scientists claim in a report published in the Breast Cancer Research journal today.
Researchers followed 32,269 women for 11 years and found that vigorous activity may protect against breast cancer, independent of body weight control.
"Notable strengths of our study include its large sample size, prospective design, high follow-up rate, and availability of relevant known or suspected breast cancer risk factors. These features enabled us to minimise any effects from other factors apart from exercise," Michael Leitzmann from the National Cancer Institute of the US National Institutes of Health said.
In contrast, the authors found that non-vigorous activity such as light housework and light exercise did not protect against the cancer.
"Possible mechanisms through which physical activity may protect against breast cancer that are independent of body mass include reduced exposure to growth factors, enhanced immune function, and decreased chronic inflammation, variables that are related both to greater physical activity and to lower breast cancer risk," Mr Leitzmann added.
"An alternative explanation for the stronger apparent effect of vigorous activity among lean over heavy women is that heavier women may misreport non-vigorous activities as vigorous ones."