Tamoxifen retains its place as the most important drug in the manageme
nt of human breast cancer. As time passes, it becomes clear that this
drug is no longer to be regarded as a simple antiestrogen, since it mo
difies other cellular signalling mechanisms, giving scientific credenc
e to the growth inhibitory effects observed in estrogen receptor-negat
ive tumours. With the role of tamoxifen in breast cancer being well do
cumented, recent interest has concentrated on its now proven efficacy
in adjuvant treatment of patients with the disease in its early stages
, and on its prophylactic role in women at high risk of developing the
disease. For tamoxifen to have any role at all in the latter situatio
n, it must be demonstrably safe, and here again the toxicity profile i
s now much better understood.