Osteoporosis drugs don't protect against breast cancer

Alendronic acid (Fosamax) is taken for
osteoporosis (NIH image)

CANCER DIGEST – Aug. 11, 2014 – Osteoporosis drugs known as bisphosphonates may not protect women from breast cancer as had been thought, according to a new study led by researchers at UC San Francisco (UCSF) despite several observational studies that showed women who took them were less likely to get breast cancer.

The new analysis stems from two clinical research study that randomly compared two versions of the drug, Fosamax and Reclast in women taking the drugs for osteoporosis. The results appeared in today’s JAMA Internal Medicine.

The Fracture Intervention Trial (FIT) randomly assigned 6,459 women aged 55-81 to alendronate (Fosamax) or placebo for an average of 3.8 years. Over that time, 1.8 percent of the women who received the drug developed breast cancer, while 1.5 percent of those given a placebo developed the disease, which means statistically there was no difference.

In the Health Outcomes and Reduced Incidence with Zoledronic Acid (Reclast) Once Yearly-Pivotal Fracture Trial (HORIZON-PFT) 7,765 women 65-89 either took an annual dose of the drug or a placebo. After an average of 2.8 years .87 percent of the women in the drug group and .77 percent of those given the placebo were diagnosed with breast cancer, also showing no statistical difference.

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