It's the news that could offer hope to thousands of women suffering one of the deadliest types of breast cancer.
A new drug unveiled in the UK is expected to cut the debilitating side effects of traditional therapy and offer several months to life expectancies.
The drug called trastuzumab emtansine – abbreviated T-DM1 – is currently being tested at the Peter MacCallum Cancer Centre in Melbourne.
"It's been the holy grail of oncology to find magic bullets – treatments which attack breast cancer without causing side effects," said Dr Eliot Sims of King George Hospital in the UK, who took part in a trialing of the drug.
"This is a huge breakthrough, and it is unusual to see such dramatic improvements."
In UK trials, remission time was usually five months longer when patients were given the drug at an early stage of treatment of HER2-positive, an incurable form of the disease.
The latest study found remission was significantly extended in patients suffering HER2-positive who had been treated with another drug, Herceptin, and whose cancer had spread.
T-DM1 is formed when the Herceptin antibody is combined with DM1, a powerful chemotherapy agent.
DM1 chemotherapy was stopped in the 1980s after it was found to damage healthy cells.
The T-DM1 combination appears to be a better option. It attaches itself to cancerous cells and prevents them from spreading. It also spurs the immune system to attack the cancerous cells, and then destroys the cell.
Women involved in the trial were less likely to lose their hair and the incidence of diarrhoea was reduced.
"For women, the side effects of chemotherapy can be severe," Dr Caitlin Palframan of Breakthrough Breast Cancer told the UK's Daily Mail.
"There's no cure for metastatic [spreading] breast cancer, so we're looking for things to delay progression or alleviate symptoms."
UK reports say the drug is expensive, however Roche, the pharmaceuticals company that produces the drug, say it's too early to speculate on cost.