Daily Walk May Cut Your Breast Cancer Risk
Study findings are good news for postmenopausal women, experts say
Those who walked seven hours or more a week, even without engaging in other recreational physical activity, reaped protective benefits compared to those who walked three hours or less a week.
The message is encouraging, Patel said.
However, the study only found an association between moderate exercise and reduced breast cancer risk, not a direct cause-and-effect relationship.
While other studies have found that exercise lowered risk of breast cancer more for women with a lower body mass index (BMI) -- a calculation of body fat based on height and weight -- this study found the effect held regardless of BMI, weight gain in adulthood or use of postmenopausal hormone therapy.
Other studies have found a link between time spent sitting and breast cancer risk, but Patel's group did not find this link.
This is "a good news study for women," said another cancer expert, Dr. Laura Kruper, who was not involved with the research.
The findings add to the accumulating evidence about exercise lowering breast cancer risk, and present a goal that is reachable for most women, said Kruper, co-director of the breast cancer program at the City of Hope Cancer Center in Duarte, Calif.
"This is something nearly every woman can do," Kruper said of exercising moderately for an hour daily.
"This is not running a marathon," she said.
Her advice to sedentary women who want to reduce their breast cancer risk: "If you get off the couch and walk around, it would help."
Why does exercise appear to lower breast cancer risk? The mechanism is mostly hormonal, Patel said. Breast cancer risk is affected by lifetime exposure to estrogen, with more exposure increasing risk. Older, physically active women have lower levels of estrogen than their sedentary peers.
Besides exercising, women who want to reduce breast cancer risk should maintain a healthy body weight, Patel said, and if they drink, they should limit alcoholic beverages to no more than one daily.