Taxotere will be added to routine chemotherapy
More than 3,000 women diagnosed at 100 hospitals across the UK are to be recruited to see if Taxotere - a drug in the same class as Taxol - can make a difference to their disease.
Taxotere has already been proven effective in women whose breast cancer is advanced, often prolonging life by years.
However, it is to be tested on women whose disease has not yet reached that stage.
Doctors are hopeful that, in these women, the drug might actually help cure their cancer rather than simply keep it at bay.
Recruitment starts
The trial, called TACT and funded by the Cancer Research Campaign, has already recruited some of the thousands of patients it needs to test the drugs.
One of those already enrolled is Edna Jewell from Sydenham Hill in south London, who said: "I was pleased to be the first woman in Britain to receive the new treatment - I'm determined to beat my cancer, and I hope this will give me the best possible chance."
Dr Paul Ellis, of Guy's and St Thomas' Hospital in London, said: "We know that Taxotere can keep very ill women alive and well for a long time, but we're now testing whether for women whose disease is less advanced it can actually work as a cure."
Dr Peter Barrett-Lee, from the Venlindre Hospital in Cardiff, said that massive trials were the only way to discover whether particular drug combinations did help patients.
"Trials like the one we are conducting are expensive and time-consuming, but more than worth it in the end in numbers of lives saved."
Breast cancer is still the most common among British women, with approximately 35,000 diagnoses every year.
Approximately two-thirds survive beyond the five-year-mark, although this figure is improving swiftly as drugs and other treatments develop.
Professor Gordon McVie, the Director General of the Cancer Research Campaign, said: "It's important to fund large-scale studies like the TACT trial, so that hospitals can make their decisions on what drugs to use based on hard, clinical evidence, rather than on cost or convenience."