Abstract | OBJECTIVES:
Tamoxifen is a partial ER antagonist that is highly effective in the treatment of receptor positive breast cancer. It significantly reduces recurrence and improves survival in both pre- and postmenopausal women. Unfortunately, many ER+ positive tumors progress despite tamoxifen treatment and until now, no possibility exists to prospectively identify tamoxifen-resistant tumors. It has been suggested that that in HER2 over-expressing tumors, cross-talk via activated HER2 receptors is a key mechanisms by which tumors become tamoxifen-resistant. METHODS: We have therefore used immunohistochemistry to analyze the expression of HER2 and activated ptyr-1248 HER2 in 408 women of ER+, early breast cancer who had received at least 2 years of adjuvant tamoxifen. We then analyzed possible associations between HER2 and pHER2 expression, and prognostic parameters, and evaluated the effect of HER2 expression and survival. RESULTS: With HER2 being positive in 12 of 208 (2.9%) of ER+ positive tumors, HER2 overexpression was found to be considerably less common in ER+ tumors than what has been thought previously. The majority of HER2 overexpressing tumors, however, also expressed the activated receptor form (r = 0.664; P < 0.0001). Both HER2 and pHER2 are moderately correlated with Grading (r = 0.138; P = 0.0052 and r = 0.118; P = 0.0241, respectively) and nodal involvement (r = 0.163; P = 0.0018 and r = 0.134; P = 0.016, respectively), but neither HER2 nor its activated form are significant predictors of RFS, DFS, or OS. CONCLUSIONS: Taken together, we have demonstrated that in ER+ breast cancer, the HER2 receptor is commonly activated, but its low prevalence in ER+ tumors does not render it a useful prognostic parameter in tamoxifen-treated patients.
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Authors | Christian F Singer, Daphne Gschwantler-Kaulich, Anneliese Fink-Retter, Georg Pfeiler, Ingrid Walter, Gernot Hudelist, Samir Helmy, Anne-Catherine Spiess, Wolfgang Lamm, Ernst Kubista |
Journal | Journal of cancer research and clinical oncology
(J Cancer Res Clin Oncol)
Vol. 135
Issue 6
Pg. 807-13
(Jun 2009)
ISSN: 1432-1335 [Electronic] Germany |
PMID | 19034514
(Publication Type: Journal Article)
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Chemical References |
- Antineoplastic Agents, Hormonal
- Receptors, Estrogen
- Tamoxifen
- Receptor, ErbB-2
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Topics |
- Adult
- Aged
- Aged, 80 and over
- Antineoplastic Agents, Hormonal
(therapeutic use)
- Breast Neoplasms
(drug therapy, metabolism, pathology)
- Female
- Humans
- Middle Aged
- Prognosis
- Receptor, ErbB-2
(biosynthesis)
- Receptors, Estrogen
(biosynthesis)
- Retrospective Studies
- Survival Analysis
- Tamoxifen
(therapeutic use)
- Time Factors
- Treatment Outcome
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