New breast cancer drug Exemestane shows great potential to save lives

Feb 13 2007

In what will be welcome news to millions of women suffering from breast cancer, trials of a new drug have found it lowers oestrogen levels in women with hormone-sensitive breast cancer and has the potential to save more than 1,000 lives a year in the UK alone.

The researchers found that switching from the breast cancer treatment Tamoxifen to the new drug Exemestane after two or three years resulted in death rates falling by 17 per cent.

The findings are the result of a study involving 4,742 women who were treated for a total of five years and monitored for another three years.

For the study the women were randomly assigned either to a full five years of Tamoxifen, or treatment with Tamoxifen followed by Exemestane.

It was found that giving the women Tamoxifen after surgery already reduced the risk of dying by 33 per cent compared with no treatment.

After another two to three years of Exemestane, plus a further three years of post-treatment follow-up, survival rates were found to be significantly improved.

The chances of the women dying were then found to be 50 per cent lower than they would have been with no chemotherapy, and 17 per cent lower than they were without the switch from Tamoxifen.

Cancer Research UK scientists involved in the study, said the treatment would prevent an estimated 1,300 deaths each year if it was made available across the UK.

Professor Charles Coombes, director of the charity's research laboratories in the UK and head of cancer medicine at Imperial College, London, says Tamoxifen has already saved the lives of many breast cancer patients and this latest research shows that success can be built on by treating women first with Tamoxifen then switching to the new drug, Exemestane.

Professor Coombes says this is the first time any hormone treatment has been shown to reduce the death rate more than Tamoxifen alone and switching drugs appears to avoid the side-effects of long-term Tamoxifen therapy, such as cancer of the womb and deep vein thrombosis.

Cancer Research say the results are very encouraging because they suggest that a sequence of Tamoxifen and Exemestane could help reduce breast cancer deaths; they will continue to follow the results of the study in order to establish how the women do in the long-term.

An estimated 31,000 post-menopausal women are diagnosed with breast cancer in the UK each year and in 80 to 85 per cent of such cases, the disease is fuelled by oestrogen.

While Tamoxifen interferes with the activity of the hormone, Exemestane reduces the levels produced in a woman's body.

The drug is sold under the brand name Aromasin, and is recommended by the National Institute for Health and Clinical Excellence (NICE) as an alternative to Tamoxifen after two to three years of initial therapy, but is not available everywhere.

Experts do caution however that the drug is not suitable for everyone.

The study is published in the Lancet medical journal.