FDA approves drug for women at cancer riskBMJ 1998; 317 doi: https://doi.org/10.1136/bmj.317.7168.1274a (Published 07 November 1998) Cite this as: BMJ 1998;317:1274
The US Food and Drug Administration has approved tamoxifen for reducing the incidence of breast cancer in high risk women–a decision condemned as hasty by European specialists, who fear that many women will derive no benefit and will be at increased risk of endometrial cancer.
The landmark approval was based on results from the large North American breast cancer prevention trial, which was halted early amid great media publicity when interim analysis showed that the incidence of breast cancer was almost halved in women taking tamoxifen.
The paper, eventually published in the Journal of the National Cancer Institute (1998;90:1371-83), showed that there were 89 cases of invasive breast cancer in the tamoxifen group, versus 175 in the placebo group. The trial involved 13175 women followed up for a median of 55 months.
The benefit was highly significant, and despite the observed excess risk of endometrial cancer, pulmonary embolism, and cataracts, Bernard Fisher and colleagues concluded that it would be “highly inappropriate” not to offer tamoxifen to women at high risk of breast cancer.
Other researchers recruiting 7000 women for the international breast cancer intervention study in Europe and Australia disagree strongly, arguing that thousands of US women may now take tamoxifen without deriving any benefit.
Ian Fentiman, of the Imperial Cancer Research Fund's breast cancer research group, said: “We still do not know how to identify who will benefit and who won't, whether taking tamoxifen prevents or just delays breast cancer, and how long women at high risk need to take the drug.
“We know that the major problems of tamoxifen come on after five years of taking it. We are likely to see more cases of endometrial carcinoma, and there may be other as yet undiscovered side effects.”