A new study done at the University of Southern California (USC) suggests that women who exercise regularly can, over the long run, dramatically reduce their risk of developing invasive and in situ breast cancer.
While other studies have shown that physical activity appears to protect women against breast cancer, this is the first study to look at exercise and its effects on invasive and in situ disease, as well as hormone receptor status.
The study —called the California Teachers Study or CTS—began in 1995 and followed 110,599 women between the ages of 22 and 79 until the end of 2002. The researchers at the Keck School of Medicine, USC, who did the study, looked specifically at how much strenuous and moderately strenuous physical activity each woman did per week. Importantly, none of the participants had breast cancer when they began the study.
During the six and a half years of the study, 2,649 women developed invasive breast cancer, and a further 593 were diagnosed with breast cancer in situ. Importantly, the researchers found that those women who did strenuous physical activities such as swimming, jogging, or aerobic activities for at least 5 hours a week every year were not as likely to develop either types of disease.
The study also showed, quite unexpectedly, that with invasive breast cancer, the benefit of long-term regular exercise appeared only in those women who were estrogen-receptor negative. This is a new finding, because earlier studies have found little or no difference in the effect of physical activity by hormone receptor status.
While this result needs to be confirmed in a second study, the investigators point out that their finding offers a promising complement to the current approaches to preventing breast cancer, namely the use of drugs that block estrogens, like tamoxifen or raloxifene. While these therapies appear to be effective in reducing the risk of estrogen-receptor-positive cancers, they do not appear to have an effect on estrogen-receptor-negative disease. So, where tamoxifen and raloxifene may not help women with estrogen-receptor negative breast cancer, exercise might—in a pre-emptive, protective way—if it’s done on a regular basis.
Overall - it’s another good reason to exercise.
If you have a comment, contact claire@knowitallhealth.com.
The study was published in the February 26th issue of the Archives of Internal medicine. (Vol. 167. No.4).
Reviewed: March 31st, 2007
What is breast cancer in situ?
Cancer that remains within the ducts or lobules of the breast.
What is invasive breast cancer?
Cancer that has spread from the milk ducts or milk-making glands within the breast, to normal tissue within the breast. This type of cancer can spread throughout the lymphatic system and the bloodstream to other parts of the body.
What is estrogen receptor status?
Cancer cells within the breast can have estrogen receptors on them. Estrogen receptors are proteins that bind estrogen circulating in the body and thereby increase the estrogen that’s accessible to the cancer cell. Estrogen-receptor–positive cancer cells have these receptors and rely on estrogen to grow. Estrogen-receptor–negative cancer cells do not have estrogen receptors, and therefore do not require estrogen. Therapies such as tamoxifen and raloxifene, which work to block estrogen receptors are not effective in estrogen-receptor negative cancer because they have nothing to block.
Breast Cancer Blogs
Please note - KIAH does not endorse, or control content on sites other than www.knowitallhealth.com While we have visited these blogs we are not responsible for their content or any interpretation thereof. The information on any website, including blog sites is intended for information purposes only and should not be taken as medical advice or substituted for professional care.
http://journals.aol.com/thinkpinkblog/ThinkPink/
http://www.thecancerblog.com/