Taking part in moderate, regular physical activity reduces the risk of breast cancer in post-menopausal women, a new study shows today (4 October 2013).
The research by the American Cancer Society adds to the growing body of evidence that exercise is linked to a reduced risk of developing the disease.
Dr Alpa Patel, who led the study, said that moderate recreational activity was associated with a 14% lower risk of breast cancer, while high physical activity was linked with a 25% lower risk compared to women who were inactive. The study appears online in Cancer Epidemiology, Biomarkers, and Prevention.
She and her colleagues compared exercise and breast cancer status in 73,615 post-menopausal women who took part in the CPS-II Nutrition Cohort, which was established by the American Cancer Society in 1992. During the 17-year study, 4,760 women in the study were diagnosed with breast cancer.
About 1 in 10 women reported that they took part in no recreational physical activity at the beginning of the study 47% reported walking as their only recreational activity. Physically active women tended to be leaner, more likely to maintain or lose weight during adulthood, more likely to drink alcohol, and less likely to currently smoke. They were also more likely to use post-menopausal hormone therapy and to have had a mammogram in the past year.
Among those who reported walking as their only activity, those who walked at least seven hours per week had a 14% lower risk of breast cancer compared to those who walked 3 or fewer hours per week.
Consistent with most other studies, this found that the most active women had 25% lower risk of breast cancer than the least active.
“Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect,” said Dr Patel.
“Our findings are particularly relevant, as people struggle with conflicting information about how much activity they need to stay healthy.
“Without any other recreational physical activities, walking on average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more."
Hildebrand JS, Gapstur SM et al. Recreational physical activity and leisure-time sitting in relation to postmenopausal breast cancer risk. Cancer Epidemiol Biomarkers Prev. 22(10); 1906-12.
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