03/05/2003 - News

Predicting tamoxifen resistance in breast cancer

By: Susan Aldridge, medical journalist, PhD


Women who have high levels of a protein found in breast tumor cells might be resistant to treatment with tamoxifen.

Although tamoxifen is an important treatment for women with breast cancer that is sensitive to estrogen, it is not always effective. Researchers at Baylor College of Medicine in the US may now have shed light on why this is.

They measured levels of a protein called AIB1 which is found in breast tumor cells in two groups of women with the disease - one taking tamoxifen and the other not taking it. They also measured a related protein called HER2. They found that women with high levels of AIB1 in women not on tamoxifen had a better prognosis and longer disease-free survival. In comparison, women on tamoxifen with AIB1 did less well. This might suggest that high AIB1 levels may be linked with resistance of tamoxifen.

What is more, women with high levels of HER2 and high AIB1 seemed to do worst of all on tamoxifen. The researchers caution that these results need to be validated by additional studies. They also wonder if another drug, such as anastrozole, might be worthwhile trying in place of tamoxifen. Anastrozole is currently being compared to tamoxifen in another trial.


Journal of the National Cancer Institute 5th March 2003

Created on: 03/05/2003
Reviewed on: 03/05/2003

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