Physical inactivity or lack of exercise may dramatically increase
risk of breast cancer, according to a new report published in the Dec 2008
issue of Cancer Causes and Control.
The report by Coyle Y.M at the University of Texas
Southwestern Medical Center in Dallas, TX says exercise lowers estrogen levels
that if high would cause a higher risk of breast cancer.
Coyle suggests that estrogen induces breast cancer by
increasing breast epithelial cell proliferation, the metabolism of estrogen to
genotoxic metabolites and the silencing of tumor suppressor genes (TSGS) that
have been implicated in breast carcinogenesis.
According to the author, animal studies suggest that exercise
slows breast tumor growth by promoting changes in cellular proliferation and
Human studies albeit limited also suggest that exercise
produces favorable changes in estrogen metabolism which in turn reduces the
risk of breast epithelial cell proliferation.
Coyle says that exercise reduces promoter
hypermethylation of TSGS in breast carcinogenesis by lowering estrogen levels.
Further research is needed to clarify the mechanisms that
relate to exercise as a negative modulator of breast cancer risk, the author
Many studies have suggested that regular physical
activity or exercise reduces risk of cancer.
One recent study involving 5,968 women led James McClain
of the National Cancer Institute and colleagues confirmed previous studies that
have shown people who did physical exercise regularly were at lower risk of
The study reported at a meeting of the American
Association for Cancer Research also found among women who were in the upper
half with regard to the amount of physical activity each week, those who slept
less than seven hours per night were 47 percent more likely to develop cancer
than those who slept longer.
One study led by Michael F Leitzmann and colleagues at
the National Cancer Institute and published in the Oct. 2008 issue of Breast
Cancer Research found that postmenopausal women with body mass index lower than
25 kg/m2 who engaged in vigorous exercise were 23 percent less likely to
develop breast cancer.
But no such
association was found in overweight and obese women.
The researchers followed up 32,000 women who enrolled in
the Breast Cancer Detection Demonstration Project Follow-up Study to examine if
there was an association between risk of breast cancer and physical exercise.
Another study led by Freedman DM and colleagues from
National Cancer Institute and published in Oct 21, 2008 issue of Cancer Causes
and Control found exercise such as walking and hiking for 10 or more hours per
week rendered the greatest protection against breast cancer in women, a 43
percent reduction in the risk.
Disclaimer: What's published on this website should be considered opinions of respective writers only and foodconsumer.org which has no political agenda nor commercial ambition may or may not endorse any opinion of any writer. No accuracy is guaranteed although writers are doing their best to provide accurate information only.
The information on this website should not be construed as medical advice and should not be used to replace professional services provided by qualified or licensed health care workers. The site serves only as a platform for writers and readers to share knowledge, experience, and information from the scientific community, organizations, government agencies and individuals.
Foodconsumer.org encourages readers who have had medical conditions to consult with licensed health care providers - conventional and or alternative medical practitioners.