A drug called clodronate (brand names, Bonefos, Clostoban Drug May Help Prevent Breast Cancer From Spreading to Bone (dateline January 5, 2003) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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Drug May Help Prevent Breast Cancer From Spreading to Bone (dateline January 5, 2003)

A drug called clodronate (brand names, Bonefos, Clostoban, Loron, Ostac) may reduce the chances that breast cancer will spread to the bone, according to new research presented at the annual meeting of the American Society for Bone and Mineral Research in San Antonio. Clondronate belongs to a class of drugs called bisphosphonates, many of which are being investigated for use in breast cancer patients. In addition to preventing the spread of breast cancer to the bone, patients who were given clondronate in the study were also less likely to die of breast cancer, compared to women who were given a placebo, an inactive pill.

When breast cancer spreads past the breast and axillary (armpit) lymph nodes, it often spreads first to the bone. These breast cancer tumors in the bone are called "bone metastases." As advanced breast cancer dissolves portions of bone, a variety of problems can occur. Bone metastases can cause pain, decreased activity, and potentially severe problems such as fractures. Other complications that can arise from bone metastases include the surgical treatment for fractures, hypercalcemia (abnormally high levels of calcium), and spinal cord compression (vertebral damage due to pressure on the spinal cord).

A group of drugs called bisphosphonates are currently used to help treat osteoporosis, a degenerative bone disease affecting mainly post-menopausal women. In patients with osteoporosis, the bone loses a significant portion of its density, greatly increasing the risk of serious fractures. One bisphosphonate, Aredia (genetic name, pamidronate disodium), has already been approved by the U.S. Food and Drug Administration (FDA) to help treat bone metastases caused by breast cancer while a number of other bisphosphonates are currently under investigation for this use.

Dr. Eugene McCloskey, Sr. of the University of Sheffield in Sheffield, England and his colleagues enrolled 1,069 women who had been diagnosed with breast cancer between 1989 and 1995. All of the women received surgery, radiation, chemotherapy and the anti-cancer drug tamoxifen as required. Then, Dr. McCloskey and his team randomly assigned some of the women in the study to receive 1,600 milligrams of clondronate each day six months into their treatment for a period of two years. The remaining women were given a placebo—an inactive pill.

The women were watched for a total of five years, during which time there was a non-significant decrease in the incidence of bone metastases among the women who were given clondronate. However, when the researchers analyzed only the two year medication period when the women were actively taking clondronate, they found that the drug did significantly reduce the number of bone metastases: 12 women developed bone metastases in the clodronate group compared with 28 women in the placebo group.

Furthermore, when evaluating the women over five years, Dr. McCloskey and his colleagues found a reduction in the number of deaths from breast cancer among the women who were given clondronate: 98 women on clondronate died from breast cancer versus 129 women who were given a placebo.

Other bisphosphonates under investigation for treating bone metastases include:

  • Didronel (generic name, etidronate)
  • Skelid (generic name, tiludronate)
  • Fosamax (generic name, alendronate)
  • Zometa (generic name, zoledronate)

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