Nuclear receptor expression as a functional biomarker for breast cancer

University of Chicago
posted on 06/08/2010

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Approximately two-thirds of all breast cancers have cells which express estrogen receptors (ER-positive). For ER-positive breast cancers, treatment with anti-estrogens, such as tamoxifen, has proven to be very effective. However, for the remaining one-third of ER-negative breast cancers (approximately 65,000 per year in the United States), anti-estrogen treatments are ineffective. In addition to ER-negative breast cancers having fewer cancer prevention and treatment strategies compared to ER-positive tumors, these cancers are often more aggressive and generally given a poor prognosis. Dr. Suzanne Conzen at the University of Chicago has identified a single, prognostic genetic marker, which can alter the treatment protocols of ER-negative breast cancer patients. Dr. Conzen's group conducted a meta-analysis of the gene expression levels in ER-negative breast cancer cells. They found that when a single gene was expressed at higher levels compared to normal cells, patients experienced a significantly worse outcome compared to patients which displayed lower nuclear receptor expression levels. Given these findings, more aggressive treatment protocols (e.g., the use of anti-angiogenic and chemotherapeutic agents) can be specifically prescribed for ER-negative patients exhibiting high expression levels of this biomarker within tumor biopsies. Gene or protein expression assays can be used to examine nuclear expression levels in the patient's biological samples prior to treatment. This prognostic biomarker has the potential to revolutionize the way in which ER-negative breast cancer is treated and has the potential to significantly decrease the high mortality and recurrence associated with this aggressive form of breast cancer.