A new generation of breast cancer drugs could be used to prevent women at high risk from developing the disease, it was revealed yesterday.

Tamoxifen has been available to patients for several years, but following a number of studies in the US and Europe, it could be used to target women with a family history of breast cancer in a preventative way.

Professor Jack Cuzick, Cancer Research UK's head of epidemiology, told delegates at the National Cancer Research Institute's conference in Birmingham, this could be help tackle 75 per cent of cases.

About 42,000 women a year are diagnosed with breast cancer, which kills about 1,000 patients a month in Britain.

Prof Cuzick explained that a new drugs, known as aromatase inhibitors, are not only effective in first treatment but can also be used as a preventative agent.

He said: "Tamoxifen behaves like a very weak oestrogen which replaces the stronger oestrogen that women normally have. It's not just superior in efficiency but we're looking at how it could be used in prevention of breast cancer because of its low toxicity.

"If we're able to identify high risk women and offer them a treatment, it could prevent them from getting breast cancer in the first place.

"Aromatase inhibitors are preventing 50 per cent more breast cancers which gives us good evidence of what we could do with Tamoxifen.

"If we could give that to 75 per cent of oestrogen positive breast cancer, that would be relevant to almost 75 per cent of breast cancer cases, that's really exciting."

Researchers are awaiting the results of the IBIS 1 study.

"Then we can have the debate over whether Tamoxifen can be used widely in this way," added Prof Cuzick.

Delegates also heard about "the new Herceptin" - Tykerb - which is a tablet built around

a small molecule which taken once a day can halve the speed of growth of cancer.

It is not yet licensed in Britain and as such no costings are available, although it is believed to be cheaper than Herceptin, which costs about £24,000 for a year's course.

Dr Peter Barrett-Lee, consultant and senior lecturer at the Velindre Cancer Centre's breast unit, said: " In one trial 70 per cent of women reported a positive response to the drug, which suggests it has survival benefits.

"But while we welcome these new drugs, like Tykerb for use in patients with HER2 breast cancer where Hereceptin doesn't work, we need to ensure they are available to all women who could benefit from them."