In continuation of my update on 
zoledronic acid, I find this info really  interesting.  Researchers from Washington  University School of Medicine in St. Louis, have found that the bone-strengthening drug zoledronic acid (Zometa) can help fight  metastatic breast  cancer when given before surgery.
 
When the drug was  given along with chemotherapy  for three months before breast  cancer surgery, it reduced the number of women who had tumor cells  in their bone  marrow at the time of surgery.
Tumors shed thousands of cells, which spread throughout the body and are  referred to as disseminated tumor cells (DTCs). Breast  cancer DTCs often lodge in bone  marrow where bone growth factors help them survive.
Chemotherapy  can increase bone turnover and bone growth factors, potentially  exacerbating the problem of DTCs in the bone, which can resurface later  to cause metastatic disease in cancer  patients.
Researchers believe that zoledronic acid inhibits the release of growth factors  that help support the growth of DTCs. 
In this randomized phase II clinical trial, researchers split 109  women with newly diagnosed stage II or stage III breast  cancer into two groups. The control group received chemotherapy  alone, while the other received a combination treatment of chemotherapy  and zoledronic acid. After three months of therapy, patients with  DTCs in their bone  marrow decreased from 43 percent to 30 percent in the combination  group, compared with a decrease from 48 percent to 47 percent in the  control group. This result approached statistical significance.
Zoledronic acid treatment with chemotherapy  had additional benefits. Women in the combination group experienced  significant gains in bone density after 12 months. This is helpful for breast  cancer patients, who often develop osteoporosis  as a side effect of chemotherapy  and other breast  cancer treatments.  
The study also suggested that zoledronic acid may help fight certain  types of breast tumors directly. Aft speculates that the drug may stop  the tumor from making its own blood supply, modify the immune system in a  way that makes it harder for tumor cells to survive or even cause the cancer  cells to commit suicide.....
Ref : http://www.ncbi.nlm.nih.gov/pubmed/20362507?dopt=Abstract