Association Between Bone Mineral Density (BMD) and Breast Cancer Risk in Older Women

National Institute of Arthritis and, Muskuloskeletal DiseasesEMBARGOED FOR RELEASE, Tuesday, Nov. 5, 1996, 4:00 PM Eastern Time, Elia Ben-Ari, NIAMS, JoAnn Pass, NIA

Older women with high bone mineral density (BMD) may have a greater risk of breast cancer than women with low BMD, according to results of a study supported by the National Institutes of Health and published in the November 6, 1996 issue of the Journal of the American Medical Association. Both breast cancer and bone density are thought to be related in part to a woman's lifetime exposure to estrogens, although both are influenced by a complex set of factors. The following NIH scientific staff members will be available to provide perspective on the significance and implications of these findings. To schedule an interview, please call the media contacts at the numbers listed below. Dr. Joan McGowan Chief, Musculoskeletal Diseases Branch National Institute of Arthritis and Musculoskeletal Diseases (NIAMS) Contact: Elia Ben-Ari Phone: 301/496-8190 Dr. Sherry Sherman Director, Hormone, Bone, and Muscle Group National Institute on Aging (NIA) Contact: JoAnn Pass Phone: 301/496-1752 Background: Association Between Bone Mineral Density (BMD) and Breast Cancer Risk in Older Women Researchers studying women aged 65 or older found that women with the highest BMD had a 2- to 2.5-fold increased risk of breast cancer compared to women with the lowest BMD. The women in the study were participants in the Study of Osteoporotic Fractures (SOF), a large observational study of white women aged 65 and older. SOF is funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the National Institute on Aging (NIA), components of the NIH.

Researchers at four clinical centers collected breast cancer data from 8,545 women in the study and followed them for an average of 3.2 years. They measured bone mineral density at the beginning of the study and collected information on breast cancer at year 1 and an average of 3.2 years later. The researchers excluded women who reported that they were on estrogen replacement therapy at the beginning of the study, leaving 97 confirmed breast cancer cases and 6,757 controls (women who did not develop breast cancer) for their analysis.

The investigators suggest that bone mineral density reflects a woman's lifetime exposure to estrogens, which is influenced by factors such as age at first menstrual period, age at menopause, and natural variations in estrogen levels among women, as well as estrogen replacement therapy. The implications of these findings for women are still unclear. More information is needed from large clinical studies of the effects of estrogen therapy on bone density and breast cancer, such as the Women's Health Initiative, to determine an overall strategy that provides the greatest health benefits and fewest risks for postmenopausal women.

Reference: J.A. Cauley, F.L. Lucas, L.H. Kuller, M.T. Vogt, W.S. Browner, S.R. Cummings. "Bone mineral density predicts the risk of breast cancer in older women. The Study of Osteoporotic Fractures." JAMA, Nov. 6, 1996.