It's been used for nearly 30 years as one of the major drugs for preventing a recurrence of breast cancer, but researchers have finally discovered that tamoxifen can cause aggressive tumours in the healthy breast.
Tamoxifen is an estrogen-blocking drug that's used in cases of early breast cancer, and to stop a recurrence in women who have had the cancer. And although it's been quite successful in blocking a second cancer outbreak, researchers have discovered only this week that the drug causes an aggressive and difficult-to-treat cancer in the healthy breast.
Women taking the drug for a long time increase the risk of developing cancer in the other breast by four times, or 440 per cent.
Researchers from the Fred Hutchinson Cancer Research Center reviewed the progress of 1,103 women with breast cancer, most of whom took tamoxifen for a long time. Of these, 369 women had a second breast cancer.
(Source: Cancer Research, 2009; 69: 6865-70).