An analysis of a woman's bone mineral density can help more accurately diagnose her risk of developing breast cancer, according to a new study. It is based on an examination of 10,000 post-menopausal women (average age 63) who took part in the Women's Health Initiative, a study conducted in 40 clinical centres throughout the US. The results suggested that incorporating bone mineral density tests in current risk assessments might significantly improve physicians' ability to predict breast cancer risk in older, postmenopausal women. Bone mineral density testing is done to diagnose osteoporosis and help assess the risk of fractures. Low bone mineral density is linked to higher risk of fractures, while normal density is linked to lower risk of fractures. It is possible that over a woman's lifetime, hormonal and other factors that lead to higher bone mineral density can also lead to higher risk of breast cancer. Studies have linked higher bone mineral density with higher breast cancer risk, and bone mineral density tests have been proposed as a potential addition to breast cancer risk models. The researchers assessed the women's initial bone mineral density level as well as their score on the Gail risk model, a well known and commonly used tool that estimates five year and lifetime risk of invasive breast cancer for women 35 years of age or older. They then followed the women for an average of approximately eight years, noting which women developed breast cancer. As expected, the study found that women with a high Gail score had a 35 percent increased risk of developing breast cancer compared to women with a lower Gail score. But the study also found a 25 percent increase in the risk of developing the disease with each unit increase in total hipbone mineral density T-score. While the two scores were independent of each other, women who had the highest scores on both assessments had a much higher risk in breast cancer. Zhao Chen of the University of Arizona Mel and Enid Zuckerman College of Public Health and her colleagues conducted the study. These findings are scheduled for publication in the Sep 1 issue of CANCER, a journal of the American Cancer Society.