The researchers found that high levels of PAX 2 were linked to longer survival for women taking tamoxifen, while tougher, tamoxifen-resistant tumors had high levels of AIB1.
This information could be used to predict which patients are likely to respond to tamoxifen, and which patients are not likely to respond to the drug, Carroll said.
"If we can identify the women who are not going to respond to tamoxifen we can think about alternative therapies, which are probably going to be more effective for these women," Carroll said.
Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, believes the finding will not have an immediate effect on treatment, but might help direct therapy in the future.
"We have learned a lot about makes a cancer cell a cancer cell, and how it works," Lichtenfeld said. "And we have also learned how to better treat breast cancer."
"Understanding these mechanisms will inevitably open up new treatment opportunities," Lichtenfeld said.
For more information on breast cancer, visit the American Cancer Society.
SOURCES: Nov. 11, 2008, teleconference with: Jason Carroll, Ph.D., Cancer Research UK Cambridge Research Institute; Len Lichtenfeld, M.D., deputy chief medical officer, American Cancer Society, Atlanta; Nov. 12, 2008, Nature, online
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