| Co-Investigator(Kenkyū-buntansha) |
TAKUBO Kaiyo Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human, Chief (00154956)
AKIYAMA Futoshi Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human, Cancer Institute, Breast Pathology, Sub-chief (50222550)
SAKAMOTO Goi Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human, Cancer Institute, Breast Pathology, Chief (80085620)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
PURPOSE. The clinicopathological importance of a second estrogen receptor, ER-β, in breast cancers has been intensely studied; however, there is still no real consensus regarding the clinical utility of an ER-β assay, probably because of the lack of standardized methodology, the presence of several ER-β isotypes (ER-β1-5, etc.) and, more importantly, the lack of convincing data on whether an ER-β status provides clinically useful information over what is already provided by the traditional estrogen receptor (ER-α)/progesterone receptor (PR) assay. A large and systematic study is needed to address these important issues.
MATERIALS AND METHODS. Archival materials of 442 invasive breast cancers from women treated with adjuvant tamoxifen monotherapy and a long follow-up period (median 11.1 years) were subjected to immunohistochemical study using four commercially available anti-ER-β antibodies; anti-ER-β1 monoclonal, anti-ER-βcx (= ER-β2) monoclonal, anti-ER-β1-3 monoclonal, and anti-ER-β1-3 polyclonal.
RESULTS. ER-β expression correlated with a favorable prognosis regardless of the antibody, although anti-ER-β1 monoclonal antibody appeared to be the best marker. In multivariate analysis, ER-β1 status emerged as an independent prognostic factor. ER-β1 status was a significant predictor of survival in postmenopausal, but not premenopausal, women. Prognostic value of ER-β1 is especially distinct among patients with ER-α-negative/PR-negative or ER-α-negative/PR-negative/HER2-negative tumors, a group of patients widely believed to be hormone unresponsive, have poor prognosis, and needing chemotherapy.
CONCLUSION. Immunohistochemical examination of ER-β1 in addition to ER-α and PR is clinically important to predict survival of patients with breast cancer treated with tamoxifen monotherapy. ER-β1 examination may optimize breast cancer treatment.
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