A treatment for brittle bones can have a dramatic effect on breast cancer when combined with chemotherapy, research has shown.

Scientists found that the two drugs acted together to slow down the growth of tumours. In mice given the therapy, growing breast tumours were almost stopped in their tracks.

A clinical trial is under way in the UK that could lead to the treatment becoming widely available to patients. Since both drugs are already well established, and need only the terms of their use to be changed, this may not take long, the researchers suggest.

The therapy involves the breast cancer chemotherapy agent doxorubicin and the bisphosphonate drug zoledronic acid.

In the mouse study, doxorubicin was given first, followed 24 hours later by zoledronic acid. When the order was reversed, or the drugs administered on their own, the treatment had little effect. The scientists said that the chemotherapy drug appeared to “prime” the tumour and make it sensitive to the bisphosphonate.

Tests showed that the treatment triggered a “suicide” response known as apoptosis in the cancer cells, causing them to self-destruct. It also blocked angiogenesis, the process by which blood vessels are created that fuel tumours with oxygen and nutrients.

The researchers, from the University of Sheffield and the University of Kuopio in Finland, published their findings in the Journal of the National Cancer Institute.

Bisphosphonates are normally used to prevent bone thinning in patients with osteoporosis. They also protect bones from the destructive effects of tumours. For this reason they are sometimes given to men with prostate cancer, which has a habit of spreading to the bones. The new study showed that zoledronic acid can have a powerful direct effect on breast cancer without any bone involvement.

The results of the clinical trial, led by Professor Robert Coleman, of the University of Sheffield, should be known this year.

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