Bone Density May Signal Breast Cancer Risk

Bone density may serve as an incidator of breast cancer risk, according to a study that found older women with high bone desnity were about two times more likely to develop tumors. The study, appearing in the Journal of the National Cancer Institute followed the health history of 8,905 women who were 65 or older and free of breast cancer. After six years, the study found, those who scored highest on three types of bone mineral density tests were also more likely to develop breast cancer. Women with high bone density were also more likely to be diagnosed with advanced breast cancer, the study found. "The results suggest that bone mineral density is one of the most powerful predictors of breast cancer, especially advanced breast cancer, among elderly women", said Dr. Jane Cauley, a researcher at the University of Pittsburgh Medical Center and a co-author of the study.

In the study, researchers measured the bone density in the wrist, forearm and heel of the women. They were then monitored for more than six years. During that period, 315 of the 8,905 developed breast cancer. Analysis showed that women in the quarter of the group with the highest bone density in the forearm were about 2.8 times as likely to develop breast cancer as those who were in the lowest bone density quarter of the group. A similar relationship ws found for the other bone density tests.

Bone density is not the cause of breast cancer, but it is an indirect measure of levels of hormone, such as testosterone and estrogen, that have been linked both to bone density and to breast cancer. Dr. Carmen Rodriguez of the American Cancer Society said a bone density test might eventually be important in assessing breast cancer risk, but it is too soon to use now as there are too many unanswered questions about accuracy. Rodriguez also noted that the study involved only older women and it is not known how bone density tests could be used for women under 65.