Several studies have shown a positive association between regular exercise and reduced risk of certain types of cancer. Now, a study from the American Cancer Society has determined a link between walking and reduced breast-cancer risk in postmenopausal women.
The study, published in Cancer Epidemiology, Biomarkers & Prevention (2013; 22 , 1906–12), involved 73,615 individuals participating in the American Cancer Society Cancer Prevention Study II Nutrition Cohort. During the intervention, 4,760 women were diagnosed with breast cancer. Using extended Cox regression, the researchers looked at recreational physical activity, walking, leisure-time sitting, estrogen receptor (ER) status and postmenopausal hormone (PMH) use.
At study completion, the researchers learned that the most active women had a 25% lower risk of breast cancer than the least active women.
“Forty-seven percent of women reported walking as their only recreational activity; among these women, a 14% lower risk was observed for ≥7 hours/week relative to ≤3 hours/week of walking,” explained the authors.
They noted that risk reductions held true regardless of BMI, weight gain, ER status, PMH use and sitting time.
“These results support an inverse association between physical activity and postmenopausal breast cancer that does not differ by ER status, BMI, weight gain or PMH use,” reported the authors. “The finding of a lower risk associated with ≥7 hours/week of walking may be of public health interest.”