For postmenopausal women, recent recreational physical activity is associated with a lower risk of invasive breast cancer, according to research published online in Cancer Epidemiology, Biomarkers & Prevention.
Agnès Fournier, Ph.D., from the CESP Centre for Research in Epidemiology and Population Health in Villejuif, France, and colleagues examined data for 59,308 postmenopausal women with 2,155 incident invasive breast cancers. Participants were followed through biennial questionnaires from 1993 to 2005.
The researchers found that the risk of invasive breast cancer was lower for women with recent (within the previous four years) recreational physical activity levels ≥12 metabolic equivalent task-hours (MET-h)/week versus those with lower levels (hazard ratio [HR], 0.90; 95 percent confidence interval [CI], 0.82 to 0.99). There was no evidence of a dose-response association beyond 12 MET-h/week.
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The magnitude of risk reduction was similar irrespective of weight change, body mass index, waist circumference, or less recent physical activity levels (five to nine years). The risk for breast cancer increased among women with levels of physical activity ≥12 MET-h/week five to nine years earlier who became less active (HR, 1.16; 95 percent CI, 1.01 to 1.35).
Their risk was not significantly lower than that of the least active women at both time points (HR, 1.06; 95 percent CI, 0.87 to 1.29).
“Our results suggest a decrease in risk associated with recent recreational physical activity even of modest levels,” the authors write. “Starting or maintaining physical activity after menopause may be beneficial regarding breast cancer risk.”