For the first time, the effect of exemestane on women’s bone health has been studied, and researchers found that, on 3 major outcome measures, age-related bone loss in postmenopausal women taking exemestane for 2 years worsened.
“The study is important because of the potential for wide-spread use of this medication by women at increased risk of developing breast cancer,” said Dr Lianne Tile, Medical Director of the Osteoporosis Clinic and Staff General Internist at University Health Network, and one of the authors of the study.
The 2-year exemestane follow-up study included 351 postmenopausal women with a median age of 61.3 years. The patients were not osteoporotic and did not receive bone medications. The women were supplemented with a daily intake of calcium and vitamin D. Baseline lumbar spine, total hip and femoral neck T-scores were above -2.0 for all study participants.
Bone mineral density (BMD) was measured by low-radiation, high-resolution peripheral quantitative computed tomography (HRpQCT).
At 2 years, the change in BMD at the distal radius was –6.1% in the exemestane group and –1.8% in the placebo group. The BMD change was –5.0% and –1.3% in the medication and non-medication groups, respectively, for the distal tibia.
The outer shell of bones can also be measured by HRpQCT, with resulting images like a “virtual biopsy.” After 2 years, the change in bone thickness was –7.9% in the exemestane group and –1.1% in the placebo group.
To assess bone mineral density at the lumbar spine and hip, dual-energy x-ray absorptiometry was used. Compared with placebo, both the spine and hip showed a decline (–2.4% vs –0.5% in the spine and –1.8% vs –0.6% in the hip).
“We found that exemestane worsens age-related bone loss by about three-fold, even in women who take adequate calcium and vitamin D,” concluded Dr Tile. “Our findings suggest that we need to weigh the individual risks and benefits when considering exemestane for the primary prevention of breast cancer. For women taking this medication, it is a good idea to have regular bone monitoring, and adequate calcium and vitamin D.”
First author Dr Angela Cheung, director of the Centre of Excellence in Skeletal Health Assessment and the Osteoporosis Program, recommended that in addition to calcium and vitamin D, women incorporate regular weight-bearing exercise into their lifestyle. These activities, such as walking, dancing, or exercising with small weights, will help preserve muscle mass, maintain balance, and prevent osteoporotic fractures.
Source: University Health Network.