Monday, September 13, 1999 Published at 11:36 GMT 12:36 UK
Doctors clash over breast cancer drug
Doctors are divided over the benefits of Tamoxifen
Doctors will clash over the benefits of giving the drug tamoxifen to all women at risk of breast cancer at the European Cancer Conference in Vienna on Monday.
But Professor Trevor Powles, of the Breast Unit at the Royal Marsden Hospital, Sutton, will argue that tamoxifen should not be routinely used to prevent breast cancer in healthy women defined as being at risk.
Dr Fisher highlighted a five-year trial of the drug carried out by his unit on 13,388 women who were at increased risk of breast cancer.
The study found that tamoxifen reduced the risk of invasive breast cancer by 49% in women aged over 35 years.
The greater the risk of breast cancer, Dr Fisher said, the greater the benefits of tamoxifen.
Thousands could benefit
He said: "Thousands of women with invasive breast cancer die each year despite 'effective' treatment.
"We therefore cannot afford to deny those at increased risk for the disease who qualify for tamoxifen the opportunity to receive it. It is a preventive agent of demonstrated efficacy."
Professor Powles, however, will point out that there were only 86 fewer breast cancers among the 6,600 women who received tamoxifen in the Pittsburgh study.
He also will also highlight two smaller trials in Italy and the UK which showed no beneficial effect of the drug.
Professor Powles said tamoxifen was associated with serious side effects such as blood clots, loss of bone mineral density in premenopausal women, an increased risk of cancer of the womb lining and menstrual and vaginal problems.
Professor Gordon McVie, director general of the CRC, said the differing results obtained by the US and European studies were partly due to differences in the women who took part.
The US study featured more women who had previously developed benign lumps, while the European studies concentrated on women who were at risk because of a history of the disease in their family.
Professor McVie said: "You cannot argue that tamoxifen did not have a remarkable effect in the US study, however because they stopped the trial early we do not know whether the drug actively prevented the disease by reversing some sort of biological lesion, or whether it simply delayed the onset of cancer."
The US Food and Drug Administration has given permission for tamoxifen to be given to healthy women at increased risk of breast cancer.
In the UK it is up to individual doctors to decide whether to prescribe the drug. However, Professor McVie recommended that women who wanted to take tamoxifen contact either the CRC or the ICRF to sign up for the on-going trial.
Breast cancer affects one in 12 women during their lifetime.