Physical activity associated with reduced breast cancer risk

January 01, 0001

Physical activity associated with reduced breast cancer risk

In this analysis by US authors of the cohort of the Nurses' Health Study, they assessed the associations of specific and total activity, queried every 2 to 4 years since 1986, with breast cancer risk. Cox proportional hazards models were used to calculate hazard ratios (HRs). Activity was measured as hours of metabolic equivalent task values (MET-h).

They found "During 20 years of follow-up (1986-2006), 4782 invasive breast cancer cases were documented among 95,396 postmenopausal women. Compared with less than 3 MET-h/wk (less than 1 h/wk walking), women engaged in higher amounts of recent total physical activity were at lower breast cancer risk (27 MET-h/wk HR, 0.85, significant). Compared with women who were least active at menopause and through follow-up (less than 9 MET-h/wk), women who increased activity were at lower risk (less than 9 MET-h/wk at menopause and 9 MET-h/wk during follow-up HR, 0.90, significant). Among specific activities modeled simultaneously, brisk walking was associated with lower risk (per 20 MET-h/wk HR, 0.91). The association with total activity did not differ significantly between estrogen and progesterone receptor-positive and -negative tumors."

The authors concluded: "Our findings suggest that moderate physical activity, including brisk walking, may reduce postmenopausal breast cancer risk and that increases in activity after menopause may be beneficial."

Another reason to recommend physical activity to middle-aged and older women.

For the full abstract, click here.

Arch Intern Med 170(19):1758-1764, 25 October 2010
© 2010 to the American Medical Association
Physical Activity and Risk of Breast Cancer Among Postmenopausal Women. A. Heather Eliassen, Susan E. Hankinson, Bernard Rosner, Michelle D. Holmes, Walter C. Willett. Correspondence to Dr. Eliassen:

Category: X. Female Genital System, Breast. Keywords: breast cancer, exercise, walking, physical activity, prospective cohort study, journal watch.
Synopsis edited by Dr Linda French, Toledo, Ohio. Posted on Global Family Doctor 9 November 2010

Pearls are an independent product of the Cochrane primary care group and are meant for educational use and not to guide clinical care.