Hope for drug as preventative

The most widely prescribed drug for treating breast cancer can also prevent the disease in healthy high-risk women, doctors say.

A review of the results of several breast cancer prevention trials showed that the drug, tamoxifen, reduced the incidence of the illness by 38 per cent.

"In our analysis we combined all the available evidence from studies using tamoxifen for breast cancer prevention collectively involving over 40,000 women - and it is clear to us now that the drug can reduce the chance of high-risk women developing the disease," Professor Jack Cuzick, of the charity Cancer Research UK, said in a statement.

The drug, launched in 1973, also reduced new cancers in the opposite breast by 46 per cent in women with tumours sensitive to the female hormone oestrogen who had already been treated for the disease.

Tamoxifen, which neutralises the action of oestrogen, which stimulates breast cancer growth, is ineffective against tumours that are not sensitive to the hormone.

But Cuzick and his colleagues, whose findings are published in the Lancet medical journal, said more research was needed to reduce the side-effects of the medication before it could be used as a preventative drug, because it was linked to a raised risk of blood clots and cancer of the lining of the womb.

"It may be possible to reduce the side-effects of tamoxifen by using a lower dose or adding low-dose aspirin."

In a cancer prevention trial of 7700 high-risk women, another drug, called raloxifene, reduced the incidence of breast cancer by 64 per cent compared with a placebo, or dummy drug.

Raloxifene is made by Eli Lilly and Co under the name Evista.

"The early data on raloxifene looks very promising. The trial shows that the drug can reduce the risk of breast cancer by 64 per cent and cause fewer side-effects than tamoxifen," Cuzick said. Doctors were eagerly awaiting the results of an American trial that directly compared the two drugs.

Tamoxifen's role in preventing cancer has been controversial. Several years ago, researchers reported that it reduced breast cancer cases by 45 per cent in a US trial which was cut short to allow women on the placebo to take tamoxifen instead.

At the time, British researchers criticised the US decision, saying long-term studies were needed to confirm the drug's effectiveness.

"The evidence to date clearly shows that tamoxifen can reduce the risk of breast cancers stimulated by the hormone oestrogen. However, it is crucial that we follow all the trials to their conclusions and find ways to reduce the side-effects of tamoxifen before we can recommend that high-risk women take the drug to prevent breast cancer," Cuzik added.


- REUTERS




Herald feature: Health