How effective are therapies to prevent bone loss in patients with breast cancer?

This study examined the effectiveness of three commonly used therapies to prevent bone loss in patients with hormone-positive breast cancer (BC). The results showed that the therapies prevented bone loss and fractures but to different degrees.

Many patients with BC are classified as hormone-positive. This means that cancer cells use hormones such as estrogen to grow. Hormone therapy helps to treat patients with hormone-positive BC. One side effect of hormone therapy is bone loss. Bone loss is the thinning of bones, meaning they are less dense and weaker. Patients who experience bone loss are more likely to suffer bone fractures. Bone loss therapies help to prevent this and include risedronate (Actonel), zoledronate (Zometa), and denosumab (Prolia). There is a lack of data comparing the effectiveness of the three medications in patients with BC.

Data from 16 clinical trials with 7699 patients with BC was examined. 312 patients received risedronate, 1708 patients received zoledronate, 1838 patients received denosumab and 3841 patients did not receive a bone loss therapy (control group). Patients were followed between 12 and 60 months.

After 1 year, risedronate improved bone density in the spine 2.35 times more than no treatment. Zoledronate improved bone density 5.45 times more than no treatment. Denosumab improved bone density 5.64 times more than no treatment. Zoledronate was 3.1 times more effective than risedronate and denosumab was 3.29 times more effective than risedronate. After 2 years, denosumab improved bone density by 66% more than zoledronate.

Risedronate reduced patients’ risks of fractures by 46%. Zoledronate reduced the risk of fracture by 16% and denosumab by 49%. 

The authors concluded that denosumab and zoledronate improved bone density more, while risedronate and denosumab more significantly reduced the risk of fractures.

The studies included in this trial had different setups which limit comparisons between studies. There were unequal numbers of patients in each group, which limits fair comparisons.