Cancer specialists have discovered a way in which the drug, tamoxifen, acts against cancer cells. Their findings show why it may be successful in preventing breast cancer in women at very high risk and also how it may halt the spread of the cancer.
About half of the 15,000 annual deaths from breast cancer are caused by the spread of the cancer, so the discovery - which the scientists are describing as 'revolutionary' - brings new hope in the search for drugs that can stop an early cancer spreading.
Tamoxifen is a well-established, hormone-type of drug which blocks the uptake of female hormone oestrogen by cancer cells. It has proved to be the most successful drug against breast cancer available.
But the new research has found that tamoxifen also enourages healthy cells to produce a cancer cell growth inhibitor, a peptide, called Transforming Growth Factor Beta 1. This appears to destroy neighbouring cancer cells. It is a powerful, short-lived type of protein which is thought to be part of a natural system of controlling the growth of organs.
Michael Baum, Professor of Surgery at the Royal Marsden Hospital, London, who directed the research, said yesterday that he believed that this action of tamoxifen might be the more important of the two. 'What is important is that this study has been with women with breast cancer and is not just a laboratory finding. If this treatment does prevent breast cancer it may open a way to discovering different and better drugs.'
He said there was also the possibility that such a new range of drugs could be successful against other cancers.
The findings, published today in the American journal Cancer Research, describe the TGF-Beta 1 action in cells as 'striking' after tamoxifen had been given to 10 women for up to three months before their breast cancer surgery.
The research, funded by the Cancer Research Campaign, also shows that the production of the powerful cell inhibitor did not seem to be affected by the type of breast cancer being treated.
A major British trial of tamoxifen, in which 15,000 healthy but high-risk women will take the drug or a placebo, is due to begin. It is part of an international survey designed to see how effective it is in preventing breast cancer.Reuse content