A new wonder drug for one of the most aggressive forms of breast cancer could allow women to survive with the disease for months longer.
The smart drug not only prevents the spread of breast cancer but its side effects are much less severe, experts at the American Society for Clinical Oncology will hear today.
The T-DM1 drug will be used to treat patients suffering from HER2-positive breast cancer - one of the most aggressive forms of the disease.
Research has found the drug keeps cancer at bay for three months longer than conventional treatments, while it is so precise the side-effects, such as hair loss and severe diarrhoea commonly associated with other forms of chemotherapy, are significantly reduced.
Professor Paul Ellis, from Guy's Hospital in London, said: "These results are remarkable because for the first time in breast cancer we have been able to significantly improve efficacy while substantially reducing many of the unpleasant side effects associated with chemotherapy.
"HER2-positive breast cancer is very aggressive and once it progresses to the advanced stage it becomes very difficult to treat, so there is a real need for new treatment options, like T-DM1, that can keep cancer at bay while maintaining patients' quality of life."
T-DM1 could be available to patients in less than a year. But it does not yet have a licence to be administered in the UK and there are concerns the NHS will not be able to afford to pay for its widespread use.
Dr Eliot Sims, from King George Hospital in Ilford, Essex, told the Mail on Sunday: "Is the emergence of T-DM1 going to cause funding problems? You bet it will.
"It's been the holy grail of oncology to find magic bullets - treatments which attack breast cancer without causing side effects. This is a huge breakthrough, and it is unusual to see such dramatic improvements."