Exercise indeed cuts death risk from breast cancer

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By David Liu davidl at foodconsumer dot org

It is not merely an association between regular exercise and reduced risk of breast cancer deaths.  A new study in the Dec 3, 2009 issue of Journal of Applied Physiology found exercise normalizes physiology and helps prevent spreading of cancer cells.

Epidemiologic studies have associated regular moderate exercise or physical activity with reduced risk of deaths after diagnosis of breast cancer.

The study led by researchers at Duke University Medical Center was intended to clarify how exercise could mechanistically reduce risk of cancer-specific and all-cause mortality in patients with diagnosed breast cancer.

M.W. Dewhirst and colleagues implanted human breast cancer cells in mice that were fed high fat diet and one group of mice were assigned voluntary wheel running and another group were made sedentary.  Tumor size was measured every three days.  After breast cancer grew to 1,500 mm or large, all experimental animals were scarified.

Test results showed breast cancer growth was comparable in both the exercise and sedentary groups.  But the physiological functions such as blood perfusion and vascularization were improved in the exercise group compared to the sedentary group.

Histological analyses also showed that intratumoral hypoxia levels were higher in the exercising mice and intratumoral vascularization leading to normalization of the tissue microenvironment in human breast cancers were increased.

"Such findings may have important implications for inhibiting tumor metastasis and improving the efficacy of conventional cancer therapies," the researchers wrote.

Breast cancer is diagnosed in more than 170,000 women in the United States each year. The disease and its complications kill about 50,000 annually.

Source:

J Appl Physiol. 2009 Dec 3.
Effect of Aerobic Exercise on Tumor Physiology in an Animal Model of Human Breast Cancer.
Jones LW, Viglianti BL, Tashjian JA, Kothadia SM, Keir ST, Freedland SJ, Potter MQ, Jung Moon E, Schroeder T, Herndon JE 2nd, Dewhirst MW.
Duke University Medical Center