Background: Adjuvant treatment of hormone receptor-positive breast cancer in postmenopausal women with aromatase inhibitors may be associated with increased bone loss.
Patients and methods: Two hundred patients were randomised to receive exemestane or tamoxifen as adjuvant treatment of hormone receptor-positive breast cancer. Bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry at baseline and after 6 and 12 months treatment.
Results: One hundred and sixty-one patients were assessable. Tamoxifen treatment resulted in a 0.5% increase from baseline in BMD at the spine, which was maintained at 12 months. Exemestane-treated patients experienced a 2.6% decrease from baseline in BMD at the spine at 6 months and a further 0.2% decrease at 12 months. There were significant differences in the changes in BMD between tamoxifen and exemestane at 6 and 12 months (P = 0.0026 and P = 0.0008, respectively). The mean changes in BMD from baseline at the total hip were also significantly different between exemestane and tamoxifen at 6 and 12 months (P = 0.0009 and P = 0.04, respectively). There was no difference between tamoxifen and exemestane in mean changes in BMD from baseline at the femoral neck.
Conclusions: Exemestane treatment resulted in an increase in bone loss at 6 months; bone loss stabilised after 6- to 12-month treatment.