Posted by on October 16, 2012 - 10:18am

Moderate to intense exercise and maintaining a healthy weight has been linked to a lower risk of breast cancer found a study conducted by the University of North Carolina’s Gillings School of Global Public Health and published in the journal Cancer.  The results still held up if women did not actively exercise in their younger years, but started a regimen later in life.

The Long Island Breast Cancer Study Project looked at the relationship between breast cancer and the environment.  Researchers studied more than 3,000 women between the ages of 20 to 98, half with and half without breast cancer.  Women who exercised 10-19 hours a week were 30% less likely to have breast cancer versus those who did not exercise.  Women who exercised during their reproductive years had the greatest benefit: a 33% reduction of breast cancer risk compared to those who did not exercise during their reproductive years.  Postmenopausal women who exercised experienced a 30% reduction in breast cancer risk compared to postmenopausal women who did not exercise.

More exercise even further reduces the risk of breast cancer.

Researchers have not definitively concluded how the link works, but they point to the decreased weight that occurs with regular exercise.  Being overweight is linked to higher rates of cancer potentially because hormone levels and inflammation is increased in overweight people.

Conversely, gaining weight increases the risk of breast cancer.  Non-active women who gained more than 6.5 pounds during their adult years raised their risk of breast cancer by 28% versus non-active women that did not gain weight.  Women who did exercise, but still gained weight had an increased risk of breast cancer compared to non-active, normal weight women meaning that gaining too much weight negates the benefits of exercise.

The results held up even when factors that may affect a participant’s breast cancer risk were accounted for.  These include the use of oral contraceptives, smoking, number of pregnancies and a family history of breast cancer.

“If you’re postmenopausal, and you have not been active, it’s not too late to get started,” lead researcher Lauren McCullough says.

You can still reduce your risk of breast cancer.  Exercise can benefit any age even if weight loss does not occur.

Researchers conclude that physical activity 10-19 hours per week during reproductive and postmenopausal years may have the greatest benefit in decreasing the risk of breast cancer.