UK. Tamoxifen is already a widely used hormonal treatment for women following treatment for early and advanced breast cancer. Now, in addition to its use as a treatment in cancer, preliminary results from the International Breast Cancer Intervention Study (IBIS) provide evidence also for the use of tamoxifen to ‘prevent’ breast cancer in healthy women at high risk. The results so far show that the incidence of breast cancer was reduced by one-third in women at high risk, compared to women taking a placebo. The study also indicated, however, that tamoxifen can increase the risk of thromboembolism, particularly during and immediately after major surgery or periods of immobility. The UK Department of Health has sent out an urgent communication with the above information to all directors of public health. The key messages in the communication may be summarised as under:

1. It is clear that the benefits for women being treated for breast cancer with tamoxifen far outweigh the risks. It is important that women taking the drug as a treatment continue to do so as there is overwhelming evidence that tamoxifen saves life among women with breast cancer. There is evidence of some increase in risk from thromboembolism with tamoxifen, especially during and immediately after major surgery or periods of immobility. Patients should be made aware of the symptoms of venous thromboembolism and if they have any sudden onset of breathlessness they should consult their doctor immediately.

2. The IBIS study gives evidence of the preventative action of tamoxifen in breast cancer. However this is not a use of tamoxifen that has yet been licensed except in the context of a trial.

3. A full analysis of all trials needs to be carried out to consider whether the benefits of preventative action outweigh potential risks.

Reference:

Urgent Communication from Chief Medical Officer, 27 Mar 2002.
Available from URL: http://www.mca.gov.uk