A cheap drug developed to prevent brittle bone disease is touted as a breakthrough in the treatment of breast cancer, British and Finnish researchers say.

The drug, zoledronic acid, when used with a common chemotherapy drug, doxorubicin, stops tumors from growing and even keeps the cancer cells at bay after the termination of treatment, the Mail Online reported.

Zoledronic acid is already used to help prevent the development of osteoporosis, or brittle bone disease. Doxorubicin, a chemotherapy drug used to treat breast cancer, appeared to prepare the tumor, making it more susceptible to zoledronic acid, said scientists from the University of Sheffield and Kuopio University in Finland.

Writing in the Journal of the National Cancer Institute, scientists said that the treatment causes cancer cells to self-destruct and blocks the growth of blood vessels needed to sustain a tumor.

The combination costs a twentieth of Herceptin, which is currently given to breast cancer patients. The new combination is being tested on 3,000 women overseas, with results due in six months.

Previous research has suggested that another brittle bone disease drug called raloxifene reduces the risk of aggressive invasive breast cancers. The drug works best in cancers caused by the sex hormone estrogen.

Breast cancer is the most commonly diagnosed form of the disease in women. Around 45,000 new cases are diagnosed in Britain every year.