Graham Beaton BHSc, ND
Doctor of Naturopathic Medicine

Several studies have shown that the risk of developing postmenopausal breast cancer is lower in women who are physically active (1). To show this, studies typically compare breast cancer rates in women who participate in regular vigorous physical activity (jogging/running, tennis, racketball) to women who are physically inactive. While these studies clearly show why physical activity is important and suggest that postmenopausal women should participate in vigorous physical activity, many women will not participate in “vigorous” physical activity due to health concerns (for instance osteoporosis) or lack of interest. Thus a question that arises, is if a woman is unable or unwilling to participate in vigorous physical activity, can their risk of breast cancer be lowered with regular moderate physical activity (i.e. walking)? A recent study published in the journal Cancer Epidemiology, Biomarkers and Prevention looked to answer this question (2).

To explore the link between breast cancer and moderate physical activity, the researchers looked at cancer rates amongst postmenopausal women who participated in the CPS-II Nutrition Cohort (a prospective study of cancer incidence established by the American Cancer institute). The researchers collected information regarding levels of weekly physical activity (walking was the predominant form of physical activity) and categorized women into 3 separate groups: those who participated in moderate physical activity less than 3 hours per week, those active for 4 to 6 hours per week, and those who were active more than 7 hours per week.

Results of the study showed that women who were moderately physically active for more than 7 hours per week had a 14% lower risk of developing breast cancer compared to those who were moderately active for less than 3 hours per week. In accordance with previous results, results also confirmed that women who participated in vigorous activity had the greatest benefits, a 25% reduction in breast cancer risk.

These results provide evidence that physical activity even at a moderate level of intensity can have a large impact on one’s risk of developing breast cancer risk and overall health.

1. Friedenreich, CM. The role of physical activity in breast cancer etiology. Semin Oncol. 2010 Jun;37(3):297-302.

2. Hildebrand, J. S. et al. Recreational Physical Activity and Leisure-Time Sitting in Relation to Postmenopausal Breast Cancer Risk. Cancer Epidemiol Biomarkers Prev. 2013 Oct;22(10):1906-12

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