Women who walk for an hour a day can cut their chance of breast cancer by 14 per cent, experts have said.
While it is well known that being active cuts risk of the disease, this is the first study to specifically look at the effect of walking.
The American Cancer Society study involved 73,615 postmenopausal women, of whom 4,760 were diagnosed with breast cancer during a 17-year follow-up.
The researchers found that moderate activity in the form of walking an hour a day was associated with a 14 per cent lower risk of the disease compared to women who were least active.
Among all women in the group, 47 per cent said walking was their only recreational activity and women were far more likely to take part in walking, dancing or aerobics than vigorous activities like running, swimming and tennis.
Among those women who reported walking as their only activity, those who walked at least seven hours per week had a 14 per cent lower risk of breast cancer compared to those who walked three or fewer hours per week.
The study also found that women who took part in more vigorous activities for an hour a day had a 25 per cent lower risk of breast cancer than the least active, which echoed findings in other studies.
The results were unaffected by factors such as a woman’s weight or whether she used hormone replacement therapy.
Alpa Patel, senior epidemiologist at the American Cancer Society in Atlanta, Georgia, said: “Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect.
“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.”
Patel said the majority of women reported some daily walking and therefore promoting walking could be an effective strategy for increasing activity.
“We were pleased to find that without any other recreational activity, just walking an average of one hour per day was associated with lower risk of breast cancer in these women.”
The authors said this was the first study to report a lower risk for breast cancer among postmenopausal women specifically related to walking.
“I would say this is encouraging news for all women who want to begin an exercise regimen but find it overwhelming,” Patel said.
The study cannot prove walking prevented any cancers. But the researchers say it could be that walking affects a woman’s hormones, insulin resistance, weight and other factors linked to breast cancer risk.
Hannah Bridges, senior information officer at UK’s Breakthrough Breast Cancer, said: “We’ve known for some time that being active can reduce a woman’s risk of breast cancer.
“Breakthrough Breast Cancer advises that 30 minutes of moderate physical activity a day (or 3.5 hours a week) can reduce breast cancer risk by at least 20 per cent.
“Any activity that raises your pulse reduces your risk – so regular brisk walks are an easy and free way to get active.”