Running from Breast Cancer
Need more motivation to get out and run? How’s this:
Posted Wednesday, 17 November, 2004
Women who exercise for three or more hours each week can reduce their risk of breast cancer by twenty to forty percent.
To our benefit, and affirming our beliefs in the positive effects of running, recent research has reconfirmed our beliefs that exercise helps prevent breast cancer.
According to the American Cancer Society (ACS), in 2004, over 215,000 women in the United States will be diagnosed with invasive breast cancer and over 40,000 will die from the disease. Moreover, there are currently about two million women living in the US who have been treated for breast cancer. As the second leading cancer in women, only after lung cancer, it is imperative that we educate ourselves about current research, prevention and treatment.
Current ACS guidelines for cancer prevention include recommendations for women to engage in at least 30 minutes of exercise each day and advise more for achieving an optimal benefit. Recent information suggests that women who exercise are 20-40% less likely to develop breast cancer than their sedentary counterparts. This means the effects of exercise on preventing breast cancer are similar to those from the use of tamoxifen, without the side effects.
The ACS has found that, in general, weight gain increases the risk of breast cancer. In the journal Cancer Epidemiology Biomarkers and Prevention (Vol. 13, No. 2), researchers found post-menopausal women who gained more than 20 pounds since age 18 have a 40% increase in risk of developing breast cancer and those who gained 70 or more pounds have double that risk. Since it is already well-documented that exercise helps to maintain a healthy body weight, it is clear that running can easily be part of the equation when lowering women’s risk of developing breast cancer. A consistent exercise program is crucial to staying at a healthy weight throughout womanhood and a consistent weight is necessary to keeping the risk of breast cancer low.
Another study (McTiernan, Harvard) suggests that the link between exercise and breast cancer protection lies in female hormones. Women with higher levels of estrogen and testosterone in their blood have a higher risk of developing breast cancer. Exercise has been shown to significantly reduce the levels of these hormones, lower insulin levels and slow the growth factors that can cause breast cancer largely because aerobic exercise burns estrogen-producing stored fat.
In fact, Dr Anne McTiernan and colleagues from the Fred Hutchinson Cancer Research Center in Seattle studied over 74,000 post-menopausal women and found a 20% reduction in the risk of developing breast cancer for the women who exercised regularly. Dr. McTiernan wrote, “We think that exercise works to lower cancer risk by lowering body fat, which in turn lowers the levels of circulating cancer-promoting hormones.”
The link between exercise and breast cancer prevention is further supported by a study of C-peptide in 32,000 women in the Nurses’ Health Study. Dr. Celia Byrne and colleagues from Harvard University found a correlation between C-peptide, a marker of insulin production, and risk for breast cancer. The 463 women from the study who developed breast cancer had the highest levels of C-peptide, increasing their risk of developing breast cancer by 70 percent compared to those women with the lowest levels. These levels were found to be lowest in women who were most physically active.
However, the beneficial effects of exercise don’t end with lowering a woman’s risk of developing breast cancer. Dr. Michelle Holmes of Brigham and Women’s Hospital in Boston recently presented evidence that exercising after being diagnosed with breast cancer reduces their risk of dying from the disease. She stated, “We know that physical activity has been shown to improve the quality of life for women with breast cancer. We conclude it may also help them live longer as well as better.” Holmes’s study found that during 16 years of follow-up, those women who exercised one to three hours each week lowered their risk of dying from breast cancer by one quarter and those who exercised between three and eight hours per week cut their risk in half.
As women runners we pay close attention to our bodies, lifestyle choices and our nutrition. It is rewarding to have confirmation that our passion for running offers positive benefits for us physiologically as well as physically and mentally.
For more information:
Breast Fitness by Anne McTiernan