Researchers at Washington University School of Medicine in St. Louis found that women treated for stage II/III breast cancer who also received a bone strengthening drug zoledronic acid were less likely to have breast tumor cells growing in their bones after three months.
The zoledronic acid is a drug that decreases bone turnover and reduces bone fractures in patients with osteoporosis.
The findings will be reported June 3 at 11 a.m. CT at the 2008 American Society of Clinical Oncology Annual Meeting in Chicago.
“Tumor cells are continually being released from the primary tumor,” says lead author Rebecca Aft, M.D., Ph.D., associate professor of surgery, faculty member of the Siteman Cancer Center and a Washington University breast surgeon at Barnes Jewish Hospital. “It is thought that the bone marrow harbors these cells and that these cells are likely to evolve into metastatic disease. We think that zoledronic acid changes the bone marrow so that cancer cells are unable to lodge there.”
The researchers randomly assigned 120 women being treated for clinical stage II/III breast cancer to receive 4 milligrams of zoledronic acid intravenously every three weeks for one year, starting with their first cycle of chemotherapy, or to receive no zoledronic acid. Stage II/III cancer means the primary tumor has spread into lymph nodes or other areas near the breast.
Of women who started with no tumor cells in their bone marrow, 88 percent remained free of tumor cells in their bone marrow if they got zoledronic acid, compared to 70 percent of those who did not receive the drug. This result approached statistical significance. The one-year results are not yet available.
Rebecca Aft says that women who receive chemotherapy for breast cancer have increased rates of bone turnover, which can release growth factors and produce a favorable environment for cancer cells. The suppression of bone turnover by zoledronic acid or other bisphosphonate drugs could make bones less friendly surroundings for cancer.
Funding from Novartis and Pfizer Inc. supported this research.
Source: Washington University School of Medicine, USA