Decreasing the dose of tamoxifen may protect women from its unwanted side effects while still preventing breast cancer.

The drug tamoxifen is known to reduce the death rate from breast cancer among women with hormone-dependent disease. It works by blocking estrogen from binding to cancer cells. But tamoxifen is a powerful drug which also increases the risk of cancer of the womb and blood clots.

Researchers in Italy now report on the effect of a lowered dose of tamoxifen. A group of 120 women with hormone-dependent breast cancer received tamoxifen at either one milligram a day, two milligrams, or the standard 20 milligram dose. Blood tests showed that 'markers' of breast cancer went down more or less equally for all three doses, suggesting that the lower doses could be as effective as the higher one.

Meanwhile, the lower doses were linked to a decrease in blood levels of clotting factors, suggesting they carry a lower risk of producing unwanted blood clots. This is a preliminary study - more work is needed before doctors can routinely recommend lowering the dose of tamoxifen for women with breast cancer or who have a high risk of the disease.

Source

Journal of the National Cancer Institute 4th June 2003