Eldecalcitol Plus Risedronate Mitigates AI-Induced Bone Loss in Postmenopausal Breast Cancer

Overview

In postmenopausal women with hormone receptor-positive early breast cancer receiving aromatase inhibitors (AIs), adding eldecalcitol to risedronate therapy significantly increased lumbar spine bone mineral density (LS-BMD) over 24 months compared to risedronate alone. Although trabecular bone score (TBS) did not differ between groups, the combination therapy showed a trend toward reduced vertebral fracture incidence.

Background

Aromatase inhibitors are standard adjuvant therapy for hormone receptor-positive early breast cancer in postmenopausal women but are associated with increased bone loss and fracture risk. Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is the gold standard for assessing osteoporosis, while trabecular bone score (TBS) provides additional information on bone microarchitecture. Bisphosphonates like risedronate are used to prevent AI-induced bone loss, and eldecalcitol, a vitamin D analog, has shown efficacy in increasing BMD in primary osteoporosis. This study evaluated whether adding eldecalcitol to risedronate improves bone quantity and quality in this patient population.

Data Highlights

Key Findings

• Eldecalcitol add-on therapy significantly increased lumbar spine BMD compared to risedronate monotherapy after 24 months (group difference 0.020 g/cm², P < .001).
• Femoral neck and total hip BMD also showed greater increases with add-on therapy.
• No significant difference was observed in trabecular bone score changes between groups.
• The incidence rate ratio for morphometric vertebral fractures was lower in the add-on group (0.292), showing a trend toward fracture risk reduction (P = .061).
• Many patients were vitamin D deficient or insufficient despite advice to take supplements, highlighting the need for active vitamin D analog therapy.

Clinical Implications

For postmenopausal women with hormone receptor-positive early breast cancer receiving aromatase inhibitors, combining eldecalcitol with risedronate may provide superior protection against AI-induced bone loss compared to bisphosphonate monotherapy. Clinicians should consider vitamin D analog supplementation in addition to bisphosphonates to optimize bone health and potentially reduce fracture risk in this vulnerable population.

Conclusion

Eldecalcitol added to risedronate therapy effectively increases lumbar spine BMD in postmenopausal breast cancer patients treated with aromatase inhibitors, offering a promising strategy to mitigate AI-associated bone loss. Further research is warranted to confirm fracture risk reduction benefits.

References

1. Clinical Research Article -- Eldecalcitol Supplementation with Risedronate Mitigates Bone Density Loss Induced by Aromatase Inhibitors in Postmenopausal Women with Breast Cancer