Bone-Building Drugs May Cut Breast Cancer Risk
Women Who Take Bisphosphonates About One-Third Less Likely to Develop Cancer
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Bisphosphonates and Breast Cancer Recurrence
The new research builds on a
study presented at last year's breast cancer meeting showing that the
intravenous bisphosphonate Zometa appears to prevent breast cancer from coming
Animal and lab research suggests that the drugs may fight breast cancer in a
number of ways -- by directly killing tumor cells, by cutting off their blood
supply, or by stimulating the immune system to mount an attack against the
tumor, Chlebowski says.
In fact, there's every reason to expect that the drugs may protect against
other types of cancer as well, he says, adding that future study testing that
hypothesis is planned.
Using Women's Health Initiative data, Chlebowski and colleagues researchers
compared breast cancer rates in 2,816 women who reported using oral
bisphosphonates at the start of the study with those of 151,592 women who said
they did not take the drugs.
The women were followed for an average of 7.8 years. During that time, 5,156
of the women developed breast cancer, with 64 of the cases among
After taking into account the women's bone mineral density, this translated
to a 31% lower risk of cancer among bisphosphonates users.
"Since bisphosphonates are prescribed for women with low bone mineral
density -- and low bone mineral density has been associated with lower breast
cancer incidence -- it's important to correct for that," Chlebowski says.
Israeli Breast Cancer Study
The second study involved more than 4,000 women in Israel, about half of
whom had breast cancer. Using pharmacy records, the researchers determined
whether the women had taken bisphosphonates.
After taking into account a variety of risk factors for breast cancer
including age, ethnicity, fruit consumption, sports activity, family history of
breast cancer, and body mass index, women who took the drugs for over a year
were 29% less likely to have breast cancer than women who did not.
Taking the drugs for longer didn't appear to offer any more protection than
taking them for one year, the study showed.
"Importantly, the tumors that developed among bisphosphonates users were
more likely to be estrogen-receptor-positive," says study head Gad Rennert, MD,
PhD, of the Technion-Israel Institute of Technology. Tumors that are fueled by
estrogen have a better prognosis.