ORLANDO, Fla. (AP) – Getting modest amounts of exercise, even just an easy half-hour walk a day, appears to substantially improve women’s chances of surviving breast cancer.

Staying active has long been thought to lower the risk of getting cancer, but a new report says it may also be an important prescription for recovery.

The study, released yesterday, found that women who exercised after breast cancer reduced their chance of dying from the disease by one-quarter to one-half, depending on how active they were.

“We know that physical activity has been shown to improve the quality of life for women with breast cancer,” said Dr. Michelle Holmes of Brigham and Women’s Hospital in Boston. “We conclude it may also help them live longer as well as better.”

Just how exercise might do this is still unclear, though experts have several theories. Whatever the biological explanation, the researchers say moderate exercise is an undeniably safe recommendation that can improve cancer survivors’ health in many ways.

Holmes presented her findings yesterday at a meeting of the American Association for Cancer Research, a gathering of 13,500 researchers in Orlando.

People who walk and get other kinds of exercise are less likely to develop many common health problems, including heart disease, high blood pressure, osteoporosis and diabetes. Several studies also suggest exercise can prevent breast and colon cancer, and it may also help stop endometrial, kidney and esophageal cancer.

Generally, doctors recommend at least 45 minutes of moderate to vigorous exercise five times a week. This might prevent colon cancer by speeding the movement of food through the intestines. Exercise might also reduce breast cancer by burning up stored fat that produces estrogen, which in turn can fuel breast cancer growth.

“Even modest exercise can have major benefits,” said John Groopman, head of environmental health sciences at Johns Hopkins school of public health.

-Associated Press