(February 7, 2012 - Insidermedicine)

A drug that can help high-risk women stave off breast cancer has been shown to accelerate bone loss in research published online ahead of print in The Lancet Oncology.

You can help reduce your risk of breast cancer by:

•    Exercising regularly

•    Limiting your drinking to one or fewer drinks per day

•    Avoiding becoming overweight or obese

Researchers from the University Health Network in Toronto conducted a substudy of a large clinical trial that evaluated the benefits of taking exemestane, a drug that suppresses the production of the hormone estrogen, to prevent breast cancer among women who were known to be at high risk for the disease. In the substudy, the investigators looked at just over 240 women who were postmenopausal and had healthy bones at the outset  of the study. Among these women, the researchers evaluated whether, over two years of treatment, there were significant changes in bone density among women taking exemestane compared with those taking a placebo.

While the women taking a placebo did experience very small decreases in bone density – a finding that is indicative of normal bone loss associated with aging – those taking exemestane had significantly greater bone density loss. In fact, greater losses in bone density with exemestane compared with placebo were found at all the sites measured in the arm, leg, hip, and spine. These findings were particularly surprising in light of the fact that all the women in the clinical trial had been assigned supplements of both calcium and vitamin D to help protect their bone health.

Today’s research demonstrates that loss of bone density is a disadvantage of taking exemestane, and this needs to be balanced against its benefits when deciding which women are most likely to be helped by the drug. The findings also indicate that women who do take exemestane to prevent breast cancer should ensure that they are taking adequate calcium and vitamin D and have their bone health assessed regularly.