Heterogene Expression des Östrogenrezeptors beim primären Mammakarzinom und disseminierten Tumorzellen im Knochenmark

Abstract

Background: The presence of epithelial cells in bone marrow (BM), i. e. a positive bone marrow status, is correlated with poor prognosis in breast cancer. The estrogen receptor (ER) status in primary tumours represents an important predictive factor in breast cancer therapy. Changes in the ER expression profile between primary and metastatic disease could have an impact on therapeutic strategies. Methods: In a panel of 35 breast cancer patients with a positive BM-status, ER expression was analysed on disseminated epithelial cells using mab CK2 directed against cytokeratin no. 18 and mab 1D5 directed against ER in the Alkaline-Phosphatase-Streptavidin-Immunogold double staining procedure. ER expression detected on epithelial cells in BM was correlated with the ER status in the corresponding primary breast tumours. Results: 23 of 35 patients (65.7%) had ER negative epithelial cells and 12 patients (34.3%) had ER positive epithelial cells in bone marrow. In 19 of 35 patients (54.3%) ER expression in the primary tumours matched ER expression on disseminated epithelial cells in bone marrow. Strikingly, 13 patients (37.1%) with an ER positive primary tumour revealed ER negative epithelial cells in bone marrow. More over, three patients (8.6%) with an ER negative primary tumour demonstrated de novo ER expression on epithelial cells in bone marrow. Conclusion: ER expression on primary tumours and disseminated epithelial cells is heterogeneous in about half of the breast cancer patients. The heterogeneity in the ER expression profile should be considered in anti-hormonal treatment strategies.