Tamoxifen risk: blood clots

Hopes of finding healthy women to test tamoxifen, the breast cancer drug, have taken a further blow following a new study from Scotland.

Researchers have discovered that women who have taken the drug for up to 14 years face a greater risk of developing thromboembolism, when the blood vessel becomes blocked by a clot.

Paradoxically, the drug also reduces the risk of heart attack, although researchers from the University of Edinburgh warn that healthy women taking the drug should be carefully monitored.

Research in the US and the UK, to test whether tamoxifen is an effective cancer preventative in healthy women, has been delayed following a rash of bad publicity surrounding the drug. As a result, few women were prepared to volunteer.

A Swedish study, in 1994, revealed the drug could cause uterine cancer after long-term use, while later research also revealed a link to gastrointestinal cancer.

The National Cancer Institute in the US and the new Edinburgh study both emphasize that the drug's risks are far outweighed by the benefits in women already suffering from breast cancer (BMJ, October 14, 1995).