MONDAY, April 9 (HealthDay News) -- About 20 percent of breast cancers have an overamplification of the estrogen receptor alpha gene ESR1, and tamoxifen treatment is particularly beneficial in this subset of women, according to study findings published online April 8 in Nature Genetics.
Ronald Simon, M.D., of the University Medical Center Hamburg Eppendorf in Hamburg, Germany, and colleagues used fluorescent in situ hybridization with an ESR1 probe to analyze a tissue microarray containing more than 2,000 breast tumor samples. Protein expression was confirmed by immunohistochemistry.
The investigators detected ESR1 gene amplification in 20.6 percent of tumor samples, with 99 percent of these showing estrogen receptor protein overexpression. About 66.6 percent of cancers without ESR1 overexpressed estrogen receptor. Women with tumors that overexpressed estrogen-receptor protein who were taking tamoxifen had longer survival if they had the ESR1 gene amplification than if they did not.
"Our data suggest that ESR1 amplification is a frequent event in proliferating breast disease and breast cancer," the authors conclude. "ESR1 amplification might be instrumental in defining a subtype of primary breast cancers, and perhaps other proliferative breast diseases, that have particularly high estrogen receptor expression and that might be optimally suited for hormonal therapy."
Abstract
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