Bisphosphonates are commonly prescribed to prevent and treat bone loss, but a growing body of evidence suggests that bisphosphonates may also have direct and indirect antitumor effects.
A few previous studies have observed a lower risk of developing a first primary breast cancer associated with bisphosphonate use. Recently, postdoctoral fellow Genevieve Monsees and colleagues from the Public Health Sciences Division conducted a population-based nested case-control study to examine the relationship between bisphosphonate use and risk of contralateral breast cancer among women with a first, primary estrogen receptor-positive(ER+) breast cancer. Compared to the risk of being diagnosed with a first primary breast cancer for women in the general population, breast cancer survivors have a two to six times greater risk of developing a second primary breast cancer in their opposite-side breast.
In a total sample of 1013 women (351 cases with contralateral breast cancer and 662 unilateral breast cancer controls), those who had ever used bisphosphonates for 6 months or longer following their first breast cancer diagnosis had nearly a 50% lower risk of contralateral breast cancer compared with women who had never used bisphosphonates. A longer duration of bisphosphonate use, as well as current use, were associated with a further reduced risk. Alendronate was the most commonly used agent, used by 88% of bisphosphonate users.
With more research bisphosphonate therapy could become a feasible strategy for reducing the risk of a second primary breast cancer among ER+ breast cancer survivors. The potential antitumor effects of these agents outside of the adjuvant setting will be an interesting area for further investigation.
Monsees GM, Malone KE, Tang MC, Newcomb, PA, Li CI. 2011. Bisphosphonate use after estrogen receptor-positive breast cancer and risk of contralateral breast cancer. Journal of the National Cancer Institute, Epub ahead of print, doi: 10.1093/jnci/djr399.