Bone density may help determine breast cancer risk

NEW YORK (Reuters Health) - A woman's bone mineral density may help doctors more accurately gauge a woman's risk of developing breast cancer, according to a new study.

In the study, researchers found a strong association between bone mineral density (BMD) and breast cancer in postmenopausal women. The association was independent of a well known tool for estimating breast cancer risk called the Gail risk model, which includes family and reproductive history, age, and race/ethnicity, along with history of breast biopsies and atypical breast findings.

The results of the study suggest that incorporating BMD tests with standard risk assessments, like the Gail model, could markedly improve doctors' ability to predict breast cancer risk in older women, the researchers say.

Prior studies have found an association between higher BMD and higher risk of breast cancer, Dr. Zhao Chen from the University of Arizona in Tucson and colleagues note in the journal Cancer.

For their research, they examined risk factors for breast cancer in 9941 older women. Over an average of 8.43 years, 327 women developed breast cancer.

At the start of the study, hip BMD and Gail risk scores were known for all of the women.

Not surprisingly, the researchers report, women with a high Gail risk score had a 35 percent increased risk for developing breast cancer compared to women with a low Gail risk score. But they also found a 25 percent increase in breast cancer risk with each unit increase in hip BMD.

While hip BMD and the Gail score were independent of each other, women who had the highest scores on both assessments had a markedly higher risk of breast cancer.

"Future studies," Chen and colleagues suggest, "should investigate whether incorporating BMD and Gail score with other risk factors, such as breast density, can further improve the identification of women at high risk for developing breast cancer."

SOURCE: Cancer, online July 28, 2008.