Arthritis drugs used on the NHS could help stop breast cancer spreading, research suggests.
Scientists believe anakinra, canakinumab and sulfasalazine could be re-purposed to help stop cancer reaching bones.
Teams from the University of Manchester and the University of Sheffield discovered that a protein released by bone marrow encouraged breast cancer cells to form secondary tumours.
Tests on mice found this molecule could be blocked by drugs used to treat arthritis.
Following treatment with anakinra, only 14% of mice in the study, published by the Nature Communications journal, developed secondary tumours.
Lead author Dr Rachel Eyre, from the University of Manchester, said: "We will look to see if similar processes are also involved in breast cancer growing in other organs. We hope to in future identify those at high risk of their breast cancer spreading, and where possible use drugs to prevent this from happening."
Around 55,000 women and 370 men are diagnosed with breast cancer each year, making it the UK's most common cancer.
About 11,500 women die from the disease each year.