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Gnant et al. Denosumab reduces fracture risk during aromatase inhibitor therapy
DOI:10.1038/bonekey.2016.43
Gnant et al. report results from a large phase 3 trial in 3420 postmenopausal women who were receiving treatment with aromatase inhibitors after diagnosis with early stage estrogen receptor-positive breast cancer.
Half of the women were given denosumab at a dose of 60 mg by subcutaneous injection every 26 weeks while half received a placebo. The denosumab-treated group had a lower number of bone fractures overall (92 cf. 176) and a significantly longer time to the first clinical fracture: hazard ratio [HR] 0·50 [95% CI 0·39–0·65], P<0·0001. No cases of osteonecrosis of the jaw were reported and the incidence and severity of adverse events did not differ between the two groups.
The authors suggest that since denosumab can substantially reduce the main side effect of aromatase inhibitors in postmenopausal women its used should be implemented in clinical practice.
Editor’s comment: This large trial provides direct evidence that achieving full estrogen deprivation in breast cancer patients by aromatase inhibitors is associated with a significant increase in risk of fragility fractures, a risk that is independent of areal bone mineral density. The study also reveals using denosumab to inhibit bone remodeling significantly reduces fracture risk in this context. However clinicians should be aware that if denosumab were stopped, bone loss would resume rapidly, particularly if aromatase inhibitors were still in use.
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