Longitudinal monitoring of denosumab-associated bone changes by REMS in postmenopausal women with ER-positive breast cancer receiving aromatase inhibitors

Background: Adjuvant endocrine therapy is the treatment for estrogenreceptor (ER)-positive breast cancer (BC). Aromatase inhibitors (AIs) reduce recurrence risk but accelerate bone loss and fracture risk. Denosumab (DmAb), an antiresorptive agent, shows promise in mitigating these effects. Aims: To assess the short-term effects of DmAb and AIs on bone health in ER-positive BC patients using Radiofrequency Echographic MultiSpectrometry (REMS) compared with DXA. Methods: Post-menopausal BC patients receiving AIs who were referred for osteoporosis assessment were retrospectively identified and classified into 2 groups according to routine clinical management: patients receiving DmAb (Group A) or any anti-osteoporotic treatment (Group B). Bone health was evaluated at baseline (T0) and after 6 (T1), 12 (T2), and 18 months (T3). DXA was performed at T0 and T2, while REMS was also performed at T1 and T3. Results: 364 patients were included in the study. Group B showed a progressive decline in spine and femoral BMD, detected at all time points. Conversely, Group A exhibited significant BMD improvements at both skeletal sites, observed at all time points. Over 18 months, lumbar spine REMS-BMD decreased of -3.92%±0.88% (p<0.0001) in Group B and increased by 5.28%±0.73% (p<0.0001) in Group A. Comparable trends were observed at the femoral site. Conclusions: This study, for the first time, quantifies the short-, mediumand long-term AIs effects on bone loss and the positive impact of DmAb on bone density recovery without radiation exposure. These findings support REMS as a reliable tool for longitudinal monitoring of treatment response in patients receiving anti-osteoporosis therapy.