The scientists from Sheffield University have found that the combination of the two relatively cheap drugs slowed down the growth of tumours in mice.
The researchers believe the combination could be better at fighting the disease than any drug cocktail currently in use.
The team say the therapy stopped the developing breast tumours in their tracks and the cancer remained at bay even after treatment had finished.
The promising results have led to a clinical trial which is now under way involving 3,000 women and the results are due in six months.
The researchers believe it could lead to the treatment becoming widely available to patients as both drugs are already well established, and need only for the terms of their use to be changed.
The combination therapy involves the breast cancer chemotherapy agent doxorubicin and the bisphosphonate drug zoledronic acid, normally used to prevent bone thinning in osteoporosis patients.
In the animal study, doxorubicin was administered first, followed 24 hours later by the zoledronic acid and this was found to be the most effect order and method.
It appears that the doxorubicin "primed" the tumour and made it sensitive to the bisphosphonate.
The scientists say tests showed that the treatment triggered a "suicide" response known as apoptosis in the cancer cells, causing them to self-destruct and also blocked angiogenesis, the process by which blood vessels are created that fuel tumours with oxygen and nutrients.
Professor Robert Coleman from Sheffield University says the research represents a very substantial breakthrough and a completely new approach to treatment which is relatively simple, is not particularly unpleasant and it could be applied to other cancers.
This legislative action is a direct response to a growing movement of parents, scientists and advocates who are raising concerns about unsafe chemicals in consumer products. Months before Congress took action, retailers and manufacturers including Wal-Mart, Toys-R-Us, Lego, Evenflo and Gerber responded to consumer outcry by announcing plans to phase out phthalates in toys. In the past year, California, Washington and Vermont restricted phthalate use in children's products.
"Public awareness is at an all-time high," said Nudelman. "Consumers are saying that the products we buy must be safe, period. The phthalate ban is a great start, and an indication that Congress is ready to consider the kind of sweeping chemical policy reform that is needed."
The Breast Cancer Fund is the leading national organization working to identify and eliminate the environmental causes of breast cancer. www.breastcancerfund.
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