Anastrozole Does Not Cause Osteoporosis in Breast Cancer Patients With Normal Bone Mineral Density at Outset

New data from a 5-year update of the bone subprotocol of the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial confirm that women with a normal bone mineral density (BMD) at the outset of treatment may be able to undergo a 5-year course of therapy with anastrozole (Arimidex) without the risk of developing osteoporosis. These trial results, a subset of data from one of the world's longest-running and largest studies of breast cancer treatment after surgery, were presented at this year's American Society for Clinical Oncology (ASCO) annual meeting in Atlanta. Anastrozole is approved for adjuvant treatment of postmenopausal women with hormone-receptor-positive early breast cancer.

Predictable, Manageable Effects

The results of this study indicate that a reduction in BMD does occur over the 5-year course of treatment with anastrozole, although there appeared to be a slowing down of the rate of bone loss in the lumbar spine in years 2 to 5. These study results provide additional evidence that bone adverse events are predictable and may be manageable, with proper monitoring, for anastrozole recipients.

The impact of aromatase inhibitors, such as anastrozole, on BMD has been an important clinical question for physicians and breast cancer patients alike. In addition, recent treatment guidelines have emphasized that additional evidence was needed regarding the effect of aromatase inhibitors on bone strength. These results provide further support for current guidelines on the use of aromatase inhibitors, such as anastrozole, for the treatment of early breast cancer in postmenopausal women, specifically in patients with normal baseline BMD measurements.

"When deciding what's best for our patients, we look to clinical evidence and guidelines to lead our choices," said Aman Buzdar, MD, professor of medicine for the department of breast medical oncology at The University of Texas M. D. Anderson Cancer Center in Houston, and chair of the steering committee for the ATAC trial. "Guidelines are now strongly recommending the use of an aromatase inhibitor in postmenopausal, hormone-receptor-positive early breast cancer patients, and Arimidex offers the longest experience and strong evidence of safety and efficacy."