Bone drug, zoledronic acid, may help in preventing the spread of cancer in women with locally advanced breast cancer, says a new study at Washington University School of Medicine in St. Louis.
The study underlined that as bones are common sites for the spread, or metastasis, of breast cancer, it is required to maintain bone density for the prevention of the spread of breast cancer.
The researchers 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.
Zoledronic acid decreases bone turnover and reduces bone fractures in patients with osteoporosis.
"Tumor cells are continually being released from the primary tumor. 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," said lead author Rebecca Aft, M.D., Ph.D.
For the study, 120 women being treated for clinical stage II/III breast cancer were assigned 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.
When diagnosed, none of the patients had evidence of metastatic disease on computed tomography (CT) and/or positron emission tomography (PET) scans. However, bone marrow samples showed that about 40 percent of the patients had detectable breast tumor cells in the bone marrow.
It has earlier been proved that women with even minuscule clusters of breast tumor cells, called micrometastases, in their bone marrow at the time of their diagnosis have an increased risk of developing large metastatic tumors later.
The researchers took bone marrow samples again three months and one year after treatment began.
According to Aft, women who receive chemotherapy for breast cancer have increased rates of bone turnover, which can release growth factors and produce a favourable environment for cancer cells.
Also, the suppression of bone turnover by zoledronic acid or other bisphosphonate drugs could make bones less friendly surroundings for cancer.
"We found that patients who are negative for tumor cells in bone marrow have a very good chance of staying negative if they take zoledronic acid," Aft said.
"If longer follow up shows that women without tumor cells in their bones do not go on to develop metastatic disease, then it would be reasonable to say that bisphosphonates will likely benefit women with locally advanced breast cancer."
The findings will be reported at the 2008 American Society of Clinical Oncology Annual Meeting in Chicago.