Bone Loss Drugs May Prevent Cancer

Women taking bisphosphonates have less chance of developing invasive breast cancer than women who don’t take the bone-strengthening drugs.

Women taking oral bisphosphonates have less chance of developing invasive breast cancer than women who don’t take the bone-strengthening drugs, researchers said Thursday at the San Antonio Breast Cancer Symposium.

An analysis of more than 150,000 women enrolled in the Women’s Health Initiative (WHI) found that roughly seven years after the study began, those taking bisphosphonates—mostly Fosamax (alendronate)—had 31 percent fewer cases of invasive breast cancer compared to women not taking a bisphosphonate. Of the 5,156 total cases of invasive breast cancer diagnosed, only 64 of those diagnoses were in bisphosphonate users. Investigators noted the analysis adjusted for factors such as differences in bone mineral density between women using bisphosphonates and non-users.

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An intravenous bisphosphonate called Zometa (zoledronic acid), a drug that helps prevent bone loss in breast cancer patients receiving hormonal therapies, has even been shown to shrink tumors, as reported by from last year’s meeting. These results are likely due to the ability of these drugs to reduce the blood supply to the tumor and stimulate immune cells, said Rowan Chlebowski, MD, PhD, lead investigator of the WHI study, during a press briefing.

Chlebowski, of the Los Angeles Biomedical Research Institute, said researchers plan to look at the possible antitumor and risk-reducing effects of bisphosphonates in all solid cancers. Because of the positive outcomes associated with bisphosphonate use in women with breast cancer, he said several randomized clinical studies are currently underway to test whether oral and intravenous bisphosphonates reduce the risk of a new contralateral tumor in women already diagnosed with breast cancer.

This article is a part of CURE’s 2009 San Antonio Breast Cancer Symposium coverage. To read more articles from SABCS 2009, visit sabcs2009.curetoday.com.