Public Release: 

Long-term safety results released for breast cancer drugs


Anastrozole is tolerated better than tamoxifen for the treatment of postmenopausal women with early-stage breast cancer after surgery, according to research published in the August issue of The Lancet Oncology. "Use of anastrozole led to a lower occurrence of adverse effects and serious adverse events and significantly fewer withdrawals from treatment than use of tamoxifen", explain the researchers.

The Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial compared use of anastrozole with that of tamoxifen in more than 6000 postmenopausal women with breast cancer that had not spread to other parts of the body. The researchers now present data after more than 5 years of follow-up, which show that no new safety concerns have emerged. Overall, adverse events did not differ between the two groups, but significantly fewer patients in the anastrozole group than in the tamoxifen group had adverse events that were related to their treatment or caused them to withdraw from treatment.

The researchers also did a risk benefit analysis of the two drugs, which took into account both the chance that the patients would have a recurrence of their breast cancer and the side-effects caused by their treatment. The analysis showed that anastrozole had a significantly better risk benefit profile, and that this benefit was greatest at 1-2 years of treatment. The researchers conclude that their findings support the use of anastrozole rather than tamoxifen as the preferred initial treatment after surgery for these women.


John Houghton
ATAC secretariat
c/o Charles Bell House
67-73 Riding House Street
London W1W 7EJ, UK
Phone: +44 20 7679 9679.

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