by Wayne Lewis and Alicia Di Rado

 
The benefits of exercise — particularly regular exercise — just keep adding up.

Researchers recently found that a long-term habit of consistent exercise appears to improve women’s chances of surviving breast cancer.

Long-term exercise can improve survival odds for breast cancer patients.

According to the findings, women who exercised moderately or strenuously an average of more than 30 minutes each week since they were teenagers had less risk of dying from their breast cancer than similar women who did little or no exercise. The protective effects were strongest among overweight women.

The findings draw from the California Teachers Study, led by City of Hope’s Leslie Bernstein, Ph.D., professor and director of the Division of Cancer Etiology.

The research focused on more than 3,500 women in the study who were diagnosed with breast cancer before 2005. The scientists compared women’s cancer outcomes and body mass indexes, as well as their exercise habits from their late teen years through menopause.

Body mass index measures body fat relative to height and weight.

The scientists found that women who exercised at an intermediate level through their adult life had a 35 percent lower risk of dying from breast cancer than less-active breast cancer patients.

They also found that intermediate-level exercisers who were overweight had an almost 50 percent lower risk of death from breast cancer. Women who exercised at a high level as adults received similar benefits.

Overweight high-level exercisers had a 59 percent lower risk of death from breast cancer.

“We know that being overweight or obese is related to a poorer prognosis in women with breast cancer, so the positive effect of activity in this population is particularly encouraging,” Bernstein said.

Exercise lowers levels of certain important hormones. This effect is especially strong among overweight women, who have higher levels of these kinds of hormones than lighter women. Researchers believe elevated levels of these hormones are linked to breast cancer, so curbing them may explain the lower risk of breast cancer-related deaths among overweight breast cancer patients.

The researchers did not study whether exercise after breast cancer diagnosis influenced women’s chances of survival. However, Bernstein noted, other studies have shown that women who are active after diagnosis are less likely to die of breast cancer or other diseases.

“We think their results are so similar to those in our study because women who exercise after diagnosis are those who have had a lifestyle throughout life that included regular exercise,” she said. “Women who make a habit of exercising tend to keep exercising.”