Regimens: Another Stride Against Cancer

By NICHOLAS BAKALAR
Published: May 31, 2005

Even a small amount of exercise - as little as three hours of walking a week - significantly extends survival among breast cancer patients, a study in the May 25 issue of The Journal of the American Medical Association has found.

The researchers, led by Dr. Michelle D. Holmes of Harvard, studied 2,987 women with Stage 1, 2 or 3 breast cancer who responded to detailed questionnaires on their exercise habits.

Although one hour of walking a week increased survival, the study found that the greatest effect, a 50 percent reduction in risk, was achieved by women who exercised the equivalent of walking three to five hours a week. More exercise did not increase the benefit.

The association of exercise with survival was particularly apparent in those who had hormone-responsive tumors, and the authors suggest that a hormonal mechanism may be responsible for the effect.

Dr. Wendy Chen, an instructor in medicine at Harvard and a co-author of the paper, said that for cardiovascular disease prevention, more exercise was always better, but that even this modest amount of walking was helpful for that as well. She emphasized that walking three to five hours a week was a realistic exercise plan.

"We're not asking people to climb a mountain or run a marathon," she said. "More exercise than this would be wonderful, but it can be hard to do more. Nowadays, most people don't get enough exercise. A manageable goal is empowering."

Although the study did not explicitly consider the question, the results suggested that exercise prior to diagnosis was irrelevant: that is, even if women began exercising only after the diagnosis of cancer, they still achieved the risk reduction.