NZ in trial of breast cancer drug

BY MARTIN JOHNSTON and the INDEPENDENT

A drug that could more than halve the incidence of breast cancer is to be tested on 10,000 women in an international trial involving New Zealand and seven other countries.

Early trials of the drug, Anastrozole, suggest that it may prevent up to 70 per cent of breast cancers, prompting some specialists to speculate that the disease might be eliminated.

"Our goal is a world without breast cancer. This is not implausible," said Professor John Forbes, co-ordinator of the Australian and New Zealand arms of the trial.

That point is distant. It will be seven to 10 years before the £10 million ($27.7 million) trial, announced in London by Cancer Research UK, delivers its results.

But scientists are hoping for big gains against the disease, which is the leading cancer killer of New Zealand women and whose incidence is rising. About 2300 women a year are diagnosed and more than 600 die.

Recruitment for the trial has begun in Britain among women aged 40 to 70 who are past menopause and considered at high risk of developing the disease. In New Zealand, recruitment is expected to start by the end of the year.

Anastrozole, licensed in 1995 for advanced breast cancer, was approved for use in early breast cancer last year.

It has been hailed as the biggest advance in drug therapy for the disease in 25 years after studies showed that it extended survival and reduced side-effects, in comparison with the hormonal treatment, Tamoxifen.

Specialists predict it will replace Tamoxifen but it costs 10 times as much at around £1000 ($2780) a year.

Professor Jack Cuzick, leader of the trial and head of statistics for Cancer Research UK, said that finding a way to prevent breast cancer was a significant challenge.

"It is not like lung cancer where we know that smoking is the primary cause and if you give up smoking you will not get cancer.

"It is not like cervical cancer where we know that screening gets rid of half to three-quarters of cases.

"With breast cancer we don't really know the primary cause and we can't say, 'If you do this you won't get breast cancer'."

Screening was worthwhile because it could detect breast cancers early but it was not the ultimate answer, he said. As a result, scientists had turned to chemo-prevention - treating women with drugs to stop the disease occurring before it had developed - but initial efforts had proved disappointing.

The United States is alone in licensing Tamoxifen for breast cancer prevention.

Anastrozole, whose brand name is Arimidex, is at least as effective as Tamoxifen in cutting cancer. This is based on evidence from women who have been treated for cancer in one breast and seen a 70 per cent reduced occurrence of the disease in the other.

Women treated with Tamoxifen had a 40 to 50 per cent reduced incidence in the second breast.

Anastrozole also causes fewer side-effects.