More than a thousand women a year will survive breast cancer thanks to a type of drug that improves survival rates by 17 per cent, new research shows today.

A study of 4,742 post-menopausal women found that switching from the present gold-standard breast cancer treatment tamoxifen to the new drug exemestane after two or three years resulted in the dramatic fall in death rates.

The study followed the progress of women who were treated for a total of five years and monitored for a further three. Women were assigned randomly to a full five years of tamoxifen, or treatment with tamoxifen followed by exemestane.

Giving women tamoxifen after surgery already reduced the risk of dying by 33 per cent. After another two to three years of exemestane, plus a further three years of posttreatment follow-up, survival was found to be significantly improved.

The chances were 50 per lower than they would have been with no drug therapy.

An estimated 31,000 post-meno-pausal women have breast cancer diagnosed in Britain each year.

In 80-85 per cent of cases, the disease is fuelled by oestrogen. Whereas tamoxifen interferes with the activity of the hormone, exemestane reduces the levels produced in a woman’s body.

The charity Cancer Research UK, whose scientists were involved in the study, said that the treatment would prevent an estimated 1,300 deaths each year.

Professor Charles Coombes, director of The Cancer Research UK Laboratories and head of cancer medicine at Imperial College, London, said: “This is the first time any hormone treatment has been shown to reduce the death rate more than tamoxifen alone.

“Switching drugs also seems to avoid the side-effects of long-term tamoxifen therapy, such as cancer of the womb and deep vein thrombosis.”

Professor John Toy, medical director of Cancer Research UK, said: “These results are really very encouraging... We will continue to follow the results of this study to see how well the women fare in the longterm.”

The drug, sold under the brand name Aromasin, is recommended by the National Institute for Health and Clinical Excellence as an alternative to tamoxifen after two to three years. However, it is not available everywhere.

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