Proteins Weaken Tamoxifen's Breast Cancer Fight
(NY, Reuters Health, 3/4/03)

When Dr. C. Kent Osborne of Baylor College of Medicine in Houston, Texas, and colleagues, studied breast tumors from 316 women with estrogen-sensitive breast cancer, the researchers found that high levels of two proteins in breast tumors, HER-2/neu, and AIB1, reduced the effectiveness of tamoxifen, a drug that blocks cancer growth by attaching to the estrogen receptors. The investigators noted that, not only were subjects with high levels of both proteins unlikely to benefit from tamoxifen, but the women with high AIB1 levels actually did better without cancer drugs like tamoxifen. In fact, among subjects who had surgery but did not receive cancer drugs, those with high levels of AIB1, a protein that helps the estrogen receptor function, were most likely to survive and remain cancerfree. These findings suggest that healthcare providers should test breast cancer patients for AIB1 before prescribing treatments.

(Journal of the National Cancer Institute 2003;95:338-340,353-361.)