November 26, 2009
Estrogen Receptor-Alpha, Breast Cancer Patients And Tamoxifen Response
Researchers have found evidence of a statistically significant survival benefit from adjuvant tamoxifen among patients whose estrogen receptor (ER)-positive tumors had high levels of phosphorylation of ER-alpha; at serine-118 (ER-alpha S118-P), according to a brief communication published online November 25 in the Journal of the National Cancer Institute.
Approximately 50% of breast carcinomas are resistant to tamoxifen. Preclinical studies have shown that ER-alpha S118-P is required for response to tamoxifen.
Researchers found evidence of a statistically significant recurrence-free survival benefit from adjuvant tamoxifen, compared with no systemic treatment, among patients whose tumors had high ER-alpha S118-P expression (23.7 vs. 72.2 recurrences per 1000 person-years) but not among patients whose tumors had low expression (51.0 vs. 57.0 recurrences per 1000 person-years). ER-alpha S118-P was not associated with a benefit among untreated patients.
"Our study highlights the importance of assessing the functionality of a drug target," the authors write. "Future studies are necessary to evaluate whether ER-alpha S118-P expression is associated with tamoxifen response among post-menopausal patients."
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