By Kathleen Dohen, HealthDay News

Older women who walk every day may reduce their risk of developing breast cancer. And, those who exercise vigorously may get even more protection, according to new research.

The study of more than 73,000 postmenopausal women found that walking at a moderate pace for an hour a day was associated with a 14 percent reduced breast cancer risk, compared to leading a sedentary lifestyle. An hour or more of daily strenuous physical activity was associated with a 25 percent reduced risk, the study found.

This is welcome news for women who aren’t very athletic.

“The nice message here is, you don’t have to go out and run a marathon to lower your breast cancer risk,” said study researcher Alpa Patel, senior epidemiologist at the American Cancer Society, which funded the study.

“Go for a nice, leisurely walk an hour a day to lower risk,” Patel advised.

Breast cancer is the leading cancer among women. In the United States, about one in eight women will develop the disease in her lifetime.

The women who reported moderate exercise walked about three miles an hour, or about a 20-minute mile. The more vigorous exercisers participated in such activities as fast walking—about 4.5 miles in an hour, the equivalent of a light jog, Patel said—moderate cycling or lap swimming.

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.

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.