Breakthrough in breast cancer prevention

The results of an Australasian study into the effectiveness of breast cancer drug tamoxifen in preventing the disease are being hailed as a milestone in cancer control.

Tamoxifen is already used to treat some existing cases of breast cancer in New Zealand, where 2000 new cases are diagnosed and 600 women die of the disease each year.

As part of an international trial involving 7000 women worldwide over the past five years, the drug was given to a group of women in Australia and New Zealand who were at high risk of contracting the disease, either through family history or through biopsies showing early indicators.

The Australia-New Zealand Breast Cancer Trial Group said that the results of the trial, showing a reduction of the incidence of the disease of up to 30 per cent, were encouraging.

"This is a milestone in breast cancer control," a spokesman said.

"It's the first time we can be sure that we can prevent breast cancer, at least in some women."

But the drug had some side-effects, including an increased risk of blood clotting and cancer of the uterus.

The risks were "potentially serious but fortunately rare", he said.

"The uterine cancer risk is not a risk for women before the menopause, it seems.

"The clotting risk probably goes across the younger and older age group spectrums."

The trial found women on hormone replacement therapy could take tamoxifen with no reduction in effectiveness and no greater risk of side-effects.

Many of the original participants had agreed to continue taking the drug as part of a continuing study on its long-term effects.

Peter Dady of the Cancer Society said the trial echoed findings released in 1998 which showed a reduction of the incidence of breast cancer of up to 45 per cent.

Ian Campbell of Waikato Hospital, who headed the New Zealand trials, said previous studies involving tamoxifen had produced mixed results, but the latest findings were significant.

"These results establish that tamoxifen does prevent about a third of breast cancers in high-risk women."

He would like further studies done over longer timeframes.

"But with these results, we are at a stage where some women with a high risk of developing breast cancer may wish to consider taking tamoxifen," he said.

He praised the New Zealand women who had the courage to take part in the study.

- NZPA

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