Eldecalcitol add-on therapy prevents bone loss in postmenopausal breast cancer patients

The addition of eldecalcitol therapy to risedronate results in increased lumbar spine (LS) bone mineral density (BMD) in osteopenic to osteoporotic postmenopausal women with breast cancer who are receiving an aromatase inhibitor (AI), according to a study.

Two hundred postmenopausal women with HR+ early breast cancer (EBC) treated with risedronate for >12 months were enrolled in this open-label randomized control trial. Of these, 196 met the eligibility criteria for the full analysis set after excluding those with no follow-up BMD data. 

The researchers advised eligible participants to take vitamin D and calcium, yet many were vitamin D deficient or insufficient. They randomized women to receive either eldecalcitol add-on therapy or risedronate monotherapy.

The group difference in the change of LS-BMD at 24 months was the primary outcome. Other outcomes were femoral neck (FN)-BMD, total hip (TH)-BMD, trabecular bone score (TBS), and the incidence of vertebral and nonvertebral fractures.

At 24 months, the increase at LS-, FN-, and TH-BMD was greater in the add-on therapy group than in the monotherapy group, with a group difference of 0.020 g/cm2 (95 percent confidence interval [CI], 0.010–0.029; p<0.001) for LS-BMD.

Morphometric vertebral fractures had an incidence rate ratio of 0.292, 95 percent CI, 0.090–1.061; p=0.061). The change in TBS was not different between groups.

“AIs cause bone loss and increase fracture risk in women with HR+ EBC,” the researchers said. “Eldecalcitol, combined with bisphosphonate, increases BMD in primary osteoporosis.”