Steps to Fight Off Breast Cancer

Breast cancer patients who walk briskly for three to five hours a week or perform equivalent amounts of other exercise reduce their risk of dying by 50%, Boston researchers reported in a study to be released today.

Even those who walk for as little as an hour a week increase their chances of survival, but walking for more than five hours a week does not provide additional benefit, according to the study, to be published in today’s Journal of the American Medical Assn.

It had previously been shown that vigorous exercise could significantly reduce the risk of developing breast cancer in the first place, but this is the first study to demonstrate that it can be a valuable therapeutic tool as well.

It follows a study published last week that demonstrated that adopting a low-fat diet could also reduce the risk of breast cancer recurrence.

Together, the studies show that a healthy lifestyle can play a major role in fighting the disease.

“This gives us an opportunity to tell women there is something they can do that is good for them and is without serious side effects,” said Debbie Saslow, director of breast and gynecological cancers for the American Cancer Society.

“A lot of new treatments don’t make a bigger difference than this, and some make even less.”

Dr. Wendy Y. Chen, a member of the team from Brigham and Women’s Hospital that conducted the study, said there was a clear-cut explanation for the improvement from exercise.

“In randomized studies, women who exercise have lower estrogen levels,” she said, and reduced concentrations of circulating hormones have been shown to increase survival in breast cancer patients.

“Women who are thinner also do [have lower estrogen levels],” she said.

“And the benefits of exercise were greater in women with hormone-sensitive tumors. It all makes sense.”

An estimated 211,240 women will develop breast cancer this year, according to the American Cancer Society, and 40,410 will die from it.

The disease is the second leading cancer killer among women, trailing only lung cancer. An estimated 2 million women now living have survived the disease.

The Nurses’ Health Study, led by Dr. Michelle D. Holmes, tracked 2,987 registered nurses who were diagnosed with breast cancer between 1984 and 1998.

They were followed until June 2002.

The women filled out questionnaires every two years providing a variety of information, including how much they exercised.

The team stratified exercise in units that were equivalent to walking for an hour a week at 2 to 2.9 mph.

In the entire group, there were 370 breast cancer recurrences and 280 deaths from breast cancer.

For women who walked one to 2.9 hours a week, the risk of death was 20% lower than for those who walked less than one hour or did not exercise at all. For those who walked three to five hours, the risk was 50% lower.

For those who walked more than five hours a week, however, the risk was reduced by only about 40%.

The researchers were unable to explain that finding.

Saslow said women should remember that the survival rate for breast cancer was high even without exercise.

“Women who are unable to be physically active should not feel that they are harming themselves if they cannot exercise,” she said.