Women who took bisphosphonates were less likely to develop invasive breast cancer than women who did not take these bone-strengthening drugs, according to a recent analysis of participants in the Women’s Health Initiative (WHI) program.
As recently presented at the San Antonio Breast Cancer Symposium, researchers detailed that breast cancer developed in only 64 out of 2,216 women who were taking bisphosphonates when entering the WHI program back in 1991. For some more perspective, 151,592 women participated in the Women's Health Initiative.
According to the findings in the new observational study, there was on average 32 percent fewer invasive breast cancers in those women who used bisphosphonates as opposed to women who did not use these medications.
Furthermore, the rate of breast cancer was 4.38 per 1,000 person-years of follow up for non-bisphosphonate users as compared to 3.29 per 1,000 person-years for women who took bisphosphonates, a class of drugs that is commonly prescribed to treat osteoporosis.
Bisphosphonates like Alendronate (e.g., Fosamax), Ibandronate (e.g., Boniva) and Risedronate (e.g, Actonel) work to increase bone strength and density, specifically by binding to the surface of damaged bone cells and inhibiting the rate of resportion, or bone breakdown by the osteoclast bone cells.
According to researchers in the recent observational study, bisphosphonates may contribute to fewer breast cancers as a result of discouraging the formation of blood vessels, which tumors grow on.